run only on PRs

.github/workflows/tests.yml

@@ -1,35 +1,22 @@
 name: CI
-on: [push, pull_request, workflow_dispatch]
+on: pull_request
 
 env:
   HOMEBREW_DEVELOPER: 1
   HOMEBREW_NO_INSTALL_FROM_API: 1
   HOMEBREW_NO_AUTO_UPDATE: 1
 
 jobs:
-  record_pull_number:
-    if: github.event_name == 'pull_request'
+  outside_container:
     runs-on: ubuntu-latest
     steps:
       - name: Show `GITHUB_ variables`.
         run: |
           printf '```\n' >> "$GITHUB_STEP_SUMMARY"
-          printf '%s\n' "$(env | grep -E '^GITHUB_')" | tee -a "$GITHUB_STEP_SUMMARY"
+          printf '%s\n' "$(env | grep -E '^GITHUB_' | sort)" | tee -a "$GITHUB_STEP_SUMMARY"
           printf '```\n' >> "$GITHUB_STEP_SUMMARY"
 
-      - name: Save pull request number
-        env:
-          PR: ${{github.event.number}}
-        run: |
-          mkdir -p pr
-          echo "$PR" > pr/number
-
-      - uses: actions/upload-artifact@v3
-        with:
-          name: pull-number
-          path: pr
-
-  tests:
+  inside_container:
     name: Miscellaneous `brew` tests
     runs-on: ubuntu-latest
     container:
@@ -43,5 +30,5 @@ jobs:
       - name: Show `GITHUB_ variables`.
         run: |
           printf '```\n' >> "$GITHUB_STEP_SUMMARY"
-          printf '%s\n' "$(env | grep -E '^GITHUB_')" | tee -a "$GITHUB_STEP_SUMMARY"
+          printf '%s\n' "$(env | grep -E '^GITHUB_' | sort)" | tee -a "$GITHUB_STEP_SUMMARY"
           printf '```\n' >> "$GITHUB_STEP_SUMMARY"