Switch to "$GITHUB_OUTPUT"; update actions/checkout to v3

- https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands
- https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#setting-an-output-parameter

.github/workflows/ci.yml

@@ -20,24 +20,24 @@ jobs:
     outputs:
       strategy: ${{ steps.generate-jobs.outputs.strategy }}
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v3
       - id: generate-jobs
         name: Generate Jobs
         run: |
           git clone --depth 1 https://github.com/docker-library/bashbrew.git -b master ~/bashbrew
           strategy="$(GENERATE_STACKBREW_LIBRARY='.github/workflows/fake-gsl.sh' ~/bashbrew/scripts/github-actions/generate.sh)"
           strategy="$(.github/workflows/munge-build.sh -c <<<"$strategy")"
           strategy="$(.github/workflows/munge-debian-unstable.sh -c <<<"$strategy")"
+          echo "strategy=$strategy" >> "$GITHUB_OUTPUT"
           jq . <<<"$strategy" # sanity check / debugging aid
-          echo "::set-output name=strategy::$strategy"
 
   test:
     needs: generate-jobs
     strategy: ${{ fromJson(needs.generate-jobs.outputs.strategy) }}
     name: ${{ matrix.name }}
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v3
       - name: Prepare Environment
         run: ${{ matrix.runs.prepare }}
       - name: Pull Dependencies

.github/workflows/verify-templating.yml

@@ -15,7 +15,7 @@ jobs:
     name: Check For Uncomitted Changes
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Apply Templates
         run: ./apply-templates.sh
       - name: Check Git Status