Update GitHub action

Bump go version to 1.16 and drop the codecov token, which is now
documented as not required for public repositories.

.github/workflows/cli.yml

@@ -15,7 +15,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        go: [1.13, 1.14, 1.15]
+        go: [1.14, 1.15, 1.16]
     name: ${{ matrix.os }} @ Go ${{ matrix.go }}
     runs-on: ${{ matrix.os }}
     steps:
@@ -38,7 +38,7 @@ jobs:
           ref: ${{ github.ref }}
 
       - name: GOFMT Check
-        if: matrix.go == 1.15 && matrix.os == 'ubuntu-latest'
+        if: matrix.go == 1.16 && matrix.os == 'ubuntu-latest'
         run: test -z $(gofmt -l .)
 
       - name: vet
@@ -51,19 +51,19 @@ jobs:
         run: go run internal/build/build.go check-binary-size
 
       - name: Upload coverage to Codecov
-        if: success() && matrix.go == 1.14 && matrix.os == 'ubuntu-latest'
+        if: success() && matrix.go == 1.16 && matrix.os == 'ubuntu-latest'
         uses: codecov/codecov-action@v1
         with:
-          token: 0a8cc73b-bb7c-480b-8626-38a461643761
           fail_ci_if_error: true
 
   test-docs:
     name: test-docs
     runs-on: ubuntu-latest
     steps:
-      - name: Set up Go 1.15
+      - name: Set up Go
         uses: actions/setup-go@v1
         with:
+          # Currently fails on 1.16
           go-version: 1.15
 
       - name: Use Node.js 12.x