chore: cancel previous GHA from the same PR (#84)

.github/workflows/buildifier.yaml

@@ -15,6 +15,6 @@ jobs:
   check:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: buildifier
         run: bazel run --enable_bzlmod //:buildifier.check

.github/workflows/ci.yaml

@@ -11,6 +11,11 @@ on:
   # Allows you to run this workflow manually from the Actions tab
   workflow_dispatch:
 
+concurrency:
+  # Cancel previous actions from the same PR: https://stackoverflow.com/a/72408109
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
 jobs:
   # matrix-prep-* steps dynamically generate a bit of JSON depending on whether our action has
   # access to repository secrets. When running on a pull_request from a fork, the author is
@@ -22,7 +27,7 @@ jobs:
     # Prepares the 'bazelversion' axis of the test matrix
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - id: bazel_6
         run: echo "bazelversion=$(head -n 1 .bazelversion)" >> $GITHUB_OUTPUT
       - id: bazel_5
@@ -35,7 +40,7 @@ jobs:
     # Prepares the 'os' axis of the test matrix
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - id: linux
         run: echo "os=ubuntu-latest" >> $GITHUB_OUTPUT
       - id: macos
@@ -76,7 +81,7 @@ jobs:
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
       # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       # Cache build and external artifacts so that the next ci build is incremental.
       # Because github action caches cannot be updated after a build, we need to

.github/workflows/release.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Mount bazel caches
         uses: actions/cache@v3
         with: