infra: docker: fix workflow to always run on master

.gitea/workflows/gentoo-utils.yml

@@ -20,19 +20,21 @@ jobs:
       - name: Check for changes before building
         id: image-changes
         run: |
-          if git diff --name-only ${{ gitea.event.before }} ${{ gitea.sha }} | grep -q '^\.docker/'; then
-            echo "changes_detected=true" >> $GITEA_OUTPUT
+          if [[ ${{ gitea.ref_name }} == ${{ gitea.event.repository.default_branch }} ]]; then
+            echo changes_detected=true >> $GITEA_OUTPUT
+          elif git diff ${{ gitea.event.before }} ${{ gitea.sha }} --no-patch --exit-code .docker; then
+            echo changes_detected=true >> $GITEA_OUTPUT
           else
-            echo "changes_detected=false" >> $GITEA_OUTPUT
+            echo changes_detected=false >> $GITEA_OUTPUT
           fi        
       -
         name: Set up Docker buildx
-        if: steps.docker-changes.outputs.changes_detected == 'true'
+        if: steps.image-changes.outputs.changes_detected == 'true'
         uses: docker/setup-buildx-action@v3
 
       -
         name: Log in to Github Container Registry
-        if: steps.docker-changes.outputs.changes_detected == 'true'
+        if: steps.image-changes.outputs.changes_detected == 'true'
         uses: docker/login-action@v3
         with:
           registry: git.epenguin.net
@@ -41,7 +43,7 @@ jobs:
 
       -
         name: Build and push
-        if: steps.docker-changes.outputs.changes_detected == 'true'
+        if: steps.image-changes.outputs.changes_detected == 'true'
         uses: docker/build-push-action@v6
         with:
           push: true