CI: try using a valid env var name

ctrueden · ctrueden · commit db8e6fbe7d80 · 2023-03-07T15:03:57.000-06:00
They aren't allowed to have dashes. Maybe that's why
GitHub Actions is skipping these two build steps?
diff --git a/.github/build.sh b/.github/build.sh
@@ -28,9 +28,9 @@ fi
 
 # Determine if cache needs to be re-generated
 if [ "$cache_modified_post" -gt "$cache_modified_pre" ]; then
-  echo "update-cache=true" >> $GITHUB_ENV
+  echo "cacheChanged=true" >> $GITHUB_ENV
 else
-  echo "update-cache=false" >> $GITHUB_ENV
+  echo "cacheChanged=false" >> $GITHUB_ENV
 fi
 
 # NB: This script exits 0, but saves the exit code for a later build step.
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
@@ -46,15 +46,15 @@ jobs:
           SIGNING_ASC: ${{ secrets.SIGNING_ASC }}
 
       - name: Delete the melting-pot cache
-        if: env.update-cache == 'true'
+        if: env.cacheChanged == 'true'
         id: delete-cache
         run: |
           gh api --method DELETE -H "Accept: application/vnd.github+json" /repos/scijava/pom-scijava/actions/caches?key=${{ runner.os }}-cache
         env:
           GITHUB_TOKEN: ${{ secrets.ACCESS_TOKEN }}
 
       - name: Save the melting-pot cache
-        if: env.update-cache == 'true'
+        if: env.cacheChanged == 'true'
         id: save-cache
         uses: actions/cache/save@v3
         with:
