.github/: Add Semver to CI steps (#2635)

.github/workflows/ci.yml

@@ -172,3 +172,26 @@ jobs:
 
     - name: Check formatting
       run: cargo fmt -- --check
+
+  rustsemver:
+    runs-on: ubuntu-latest
+    steps:
+
+    - uses: actions-rs/toolchain@v1
+      with:
+        profile: minimal
+        toolchain: nightly-2022-04-20
+        override: true
+        components: rustc-dev,llvm-tools-preview
+
+    - name: Install semver
+      run: cargo install semver
+
+    - name: Fetch the version in the manifest
+      run: eval "current_version=$(grep -e '^version = .*$' Cargo.toml | cut -d ' ' -f 3)"
+
+    - name: Enforce semantic versioning
+      run: cargo semver | tee semver_out
+
+    - name: Check for semantic versioning errors
+      run: (head -n 1 semver_out | grep "\-> $current_version") || (echo "versioning mismatch" && return 1)