Prevent issues with Docker Hub rate limits in CI (#124)

Switches to the new GitHub Actions runner groups to:
1. Avoid the rate limit issues mentioned in:
   heroku/buildpacks-go#283
2. To update to Ubuntu 24.04

Also pre-pulls the builder and run images to prevent duplicate
pulls and impact on rate limits, as mentioned in:
heroku/buildpacks-python#223

See also:
https://salesforce.quip.com/bu6UA0KImOxJ#temp:C:GZR57becb9df8d94f80b132168fd
https://github.com/actions/runner-images/blob/main/images/ubuntu/Ubuntu2404-Readme.md

GUS-W-16238120.

.github/workflows/check_changelog.yml

@@ -9,7 +9,7 @@ permissions:
 
 jobs:
   check-changelog:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     if: (!contains(github.event.pull_request.labels.*.name, 'skip changelog'))
     steps:
       - name: Checkout

.github/workflows/ci.yml

@@ -15,7 +15,7 @@ env:
 
 jobs:
   lint:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -29,7 +29,7 @@ jobs:
         run: cargo fmt -- --check
 
   unit-test:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -51,7 +51,7 @@ jobs:
             arch: "arm64"
           - builder: "builder:20"
             arch: "arm64"
-    runs-on: ${{ matrix.arch == 'arm64' && 'pub-hk-ubuntu-22.04-arm-medium' || 'ubuntu-latest' }}
+    runs-on: ${{ matrix.arch == 'arm64' && 'pub-hk-ubuntu-24.04-arm-medium' || 'ubuntu-24.04' }}
     env:
       INTEGRATION_TEST_CNB_BUILDER: heroku/${{ matrix.builder }}
     steps:
@@ -69,8 +69,18 @@ jobs:
         uses: Swatinem/[email protected]
       - name: Install Pack CLI
         uses: buildpacks/github-actions/[email protected]
+      # The images are pulled up front to prevent duplicate pulls due to the tests being run concurrently.
       - name: Pull builder image
         run: docker pull ${{ env.INTEGRATION_TEST_CNB_BUILDER }}
+      - name: Pull run image
+        # Using `docker inspect` rather than `pack builder inspect` since the latter makes
+        # additional requests to Docker Hub even when the image is available locally.
+        run: |
+          RUN_IMAGE=$(
+            docker inspect --format='{{index .Config.Labels "io.buildpacks.builder.metadata"}}' '${{ env.INTEGRATION_TEST_CNB_BUILDER }}' \
+              | jq --exit-status --raw-output '.stack.runImage.image'
+          )
+          docker pull "${RUN_IMAGE}"
       # The integration tests are annotated with the `ignore` attribute, allowing us to run
       # only those and not the unit tests, via the `--ignored` option. On the latest stack
       # we run all integration tests, but on older stacks we only run stack-specific tests.