diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 3b66850..779aeb4 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -1,9 +1,5 @@
 name: CI
-on:
-  push:
-    branches:
-      - staging
-      - trying
+on: merge_group
 
 jobs:
 
@@ -21,7 +17,12 @@ jobs:
           nightly
         ]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
+      - uses: actions/cache@v4
+        if: startsWith(matrix.rust, '1')
+        with:
+          path: ~/.cargo/registry/index
+          key: cargo-${{ matrix.rust }}-git-index
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
@@ -33,7 +34,7 @@ jobs:
     name: No Std
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
         with:
           target: thumbv6m-none-eabi
@@ -43,8 +44,23 @@ jobs:
     name: Format
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@1.62.0
         with:
           components: rustfmt
       - run: cargo fmt --all --check
+
+  # One job that "summarizes" the success state of this pipeline. This can then be added to branch
+  # protection, rather than having to add each job separately.
+  success:
+    name: Success
+    runs-on: ubuntu-latest
+    needs: [test, no_std, fmt]
+    # Github branch protection is exceedingly silly and treats "jobs skipped because a dependency
+    # failed" as success. So we have to do some contortions to ensure the job fails if any of its
+    # dependencies fails.
+    if: always() # make sure this is never "skipped"
+    steps:
+      # Manually check the status of all dependencies. `if: failure()` does not work.
+      - name: check if any dependency failed
+        run: jq --exit-status 'all(.result == "success")' <<< '${{ toJson(needs) }}'
diff --git a/.github/workflows/master.yaml b/.github/workflows/master.yaml
index 98e8f8e..68c4900 100644
--- a/.github/workflows/master.yaml
+++ b/.github/workflows/master.yaml
@@ -15,7 +15,12 @@ jobs:
       matrix:
         rust: [1.31.0, stable]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
+      - uses: actions/cache@v4
+        if: startsWith(matrix.rust, '1')
+        with:
+          path: ~/.cargo/registry/index
+          key: cargo-${{ matrix.rust }}-git-index
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
diff --git a/.github/workflows/pr.yaml b/.github/workflows/pr.yaml
index d221a73..787f908 100644
--- a/.github/workflows/pr.yaml
+++ b/.github/workflows/pr.yaml
@@ -11,7 +11,12 @@ jobs:
       matrix:
         rust: [1.31.0, stable]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
+      - uses: actions/cache@v4
+        if: startsWith(matrix.rust, '1')
+        with:
+          path: ~/.cargo/registry/index
+          key: cargo-${{ matrix.rust }}-git-index
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
@@ -22,8 +27,23 @@ jobs:
     name: Format
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@1.62.0
         with:
           components: rustfmt
       - run: cargo fmt --all --check
+
+  # One job that "summarizes" the success state of this pipeline. This can then be added to branch
+  # protection, rather than having to add each job separately.
+  success:
+    name: Success
+    runs-on: ubuntu-latest
+    needs: [test, fmt]
+    # Github branch protection is exceedingly silly and treats "jobs skipped because a dependency
+    # failed" as success. So we have to do some contortions to ensure the job fails if any of its
+    # dependencies fails.
+    if: always() # make sure this is never "skipped"
+    steps:
+      # Manually check the status of all dependencies. `if: failure()` does not work.
+      - name: check if any dependency failed
+        run: jq --exit-status 'all(.result == "success")' <<< '${{ toJson(needs) }}'
diff --git a/Cargo.toml b/Cargo.toml
index b017e3f..39de2df 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,7 +10,7 @@ name = "num-complex"
 repository = "https://github.com/rust-num/num-complex"
 version = "0.4.4"
 readme = "README.md"
-exclude = ["/bors.toml", "/ci/*", "/.github/*"]
+exclude = ["/ci/*", "/.github/*"]
 edition = "2018"
 
 [package.metadata.docs.rs]
diff --git a/bors.toml b/bors.toml
deleted file mode 100644
index 67d134f..0000000
--- a/bors.toml
+++ /dev/null
@@ -1,10 +0,0 @@
-status = [
-  "Test (1.31.0)",
-  "Test (1.36.0)",
-  "Test (1.54.0)",
-  "Test (stable)",
-  "Test (beta)",
-  "Test (nightly)",
-  "No Std",
-  "Format",
-]
diff --git a/ci/test_full.sh b/ci/test_full.sh
index 60e9740..4b29bb7 100755
--- a/ci/test_full.sh
+++ b/ci/test_full.sh
@@ -40,6 +40,7 @@ check_version 1.43 || cargo update -p libm --precise 0.2.5
 
 # Some crates moved to Rust 1.56 / 2021
 check_version 1.56 || (
+  cargo update -p serde --precise 1.0.185
   cargo update -p quote --precise 1.0.30
   cargo update -p proc-macro2 --precise 1.0.65
   cargo update -p rkyv --precise 0.7.40