Fix the publish workflow rejected for using runner.temp in job env

.github/workflows/publish.yml

@@ -35,9 +35,14 @@ jobs:
     timeout-minutes: 20
     env:
       GH_TOKEN: ${{ github.token }}
-      PLAN: ${{ runner.temp }}/versions.json
-      NOTES: ${{ runner.temp }}/notes.md
     steps:
+      # The runner context is not available in job-level env.
+      - run: |
+          {
+            echo "PLAN=$RUNNER_TEMP/versions.json"
+            echo "NOTES=$RUNNER_TEMP/notes.md"
+          } >> "$GITHUB_ENV"
+
       - uses: actions/checkout@v6
         with:
           fetch-depth: 0 # the plan compares against the previous release tag
@@ -58,13 +63,17 @@ jobs:
               v[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9].[0-9][0-9]) ;;
               *) echo "::error::Release tags look like v20261008.01, got $TAG"; exit 1 ;;
             esac
-            echo "tag=$TAG" >> "$GITHUB_OUTPUT"
-            echo "dist-tag=latest" >> "$GITHUB_OUTPUT"
-            echo "dry-run=$PRERELEASE" >> "$GITHUB_OUTPUT"
+            {
+              echo "tag=$TAG"
+              echo "dist-tag=latest"
+              echo "dry-run=$PRERELEASE"
+            } >> "$GITHUB_OUTPUT"
           else
-            echo "tag=$GITHUB_SHA" >> "$GITHUB_OUTPUT"
-            echo "dist-tag=next" >> "$GITHUB_OUTPUT"
-            echo "dry-run=false" >> "$GITHUB_OUTPUT"
+            {
+              echo "tag=$GITHUB_SHA"
+              echo "dist-tag=next"
+              echo "dry-run=false"
+            } >> "$GITHUB_OUTPUT"
           fi
           # Newest published, non-pre-release Release other than this one.
           previous=$(gh release list --exclude-drafts --exclude-pre-releases \