feat(ci): cache registry baseline rustdoc JSON

The latest release (v0.18) of `cargo semver-checks` includes a [feature](obi1kenobi/cargo-semver-checks#339) where the rustdoc JSON files for registry baselines is cached in `target/semver-checks/cache`. The rustdoc JSON files for released crates never changes as the source code on crates.io cannot be changed once a version is published. Thus, it is unnecessary to generate that JSON on every CI run.

We extract a separate action that installs `cargo semver-checks` for us and also sets up a cache. The cache is scoped to released version of the crate, meaning it automatically invalidates once we publish a new version.

This speeds up the `cargo semver-checks` step by 50% which is ~ 1 minute per job.

Pull-Request: #3469.

.github/actions/cargo-semver-checks/action.yml

@@ -0,0 +1,28 @@
+name: "Run cargo semver-checks"
+description: "Install and run the cargo semver-checks tool"
+inputs:
+  crate:
+    required: true
+    description: "The crate to run `cargo semver-checks` on."
+runs:
+  using: "composite"
+  steps:
+    - run: wget -q -O- https://github.com/obi1kenobi/cargo-semver-checks/releases/download/v0.18.3/cargo-semver-checks-x86_64-unknown-linux-gnu.tar.gz | tar -xz -C ~/.cargo/bin
+      shell: bash
+
+    - name: Get released version
+      shell: bash
+      id: get-released-version
+      run: |
+        MAX_STABLE_VERSION=$(curl https://crates.io/api/v1/crates/${{ inputs.crate }} --silent | jq '.crate.max_stable_version')
+        echo "version=${MAX_STABLE_VERSION}" >> $GITHUB_OUTPUT
+
+    - uses: actions/cache@v3
+      with:
+        path: ${{ github.workspace }}/target/semver-checks/cache
+        key: semver-checks-cache-${{ inputs.crate }}-${{ steps.get-released-version.outputs.version }}
+
+    - run: cargo semver-checks check-release --package ${{ inputs.crate }} --verbose
+      shell: bash
+      env:
+        CARGO_TERM_VERBOSE: "true"

.github/workflows/cache-factory.yml

@@ -70,6 +70,3 @@ jobs:
 
       - name: Compile workspace with stable Rust
         run: cargo test --all-features --all-targets --workspace --no-run
-
-      - name: Render docs
-        run: cargo doc --all-features --workspace

.github/workflows/ci.yml

@@ -69,11 +69,10 @@ jobs:
           echo "code=${RESPONSE_CODE}"
           echo "code=${RESPONSE_CODE}" >> $GITHUB_OUTPUT
 
-      - name: Check public API for semver violations
+      - uses: ./.github/actions/cargo-semver-checks
         if: steps.check-released.outputs.code == 200 # Workaround until https://github.com/obi1kenobi/cargo-semver-check/issues/146 is shipped.
-        run: |
-          wget -q -O- https://github.com/obi1kenobi/cargo-semver-checks/releases/download/v0.17.1/cargo-semver-checks-x86_64-unknown-linux-gnu.tar.gz | tar -xz -C ~/.cargo/bin
-          cargo semver-checks check-release -p ${{ matrix.crate }}
+        with:
+          crate: ${{ matrix.crate }}
 
       - name: Enforce no dependency on meta crate
         run: |