php-fpm: tag as -latest instead of -stable

Practically speaking since I'm not testing literally any of this right
now, it should be treated as a latest release. Long-term it would
probably be wise to roll out a dedicated WordPress site and have a
latest -> stable promotion process that pushes the WordPress site to
the latest and performs a healthcheck before retagging.

.github/workflows/php-fpm.yml

@@ -72,7 +72,7 @@ jobs:
         with:
           images: gitea.auvem.com/auvem/wordpress-docker/php-fpm
           tags: |
-            type=raw,value=${{ matrix.lane }}-stable
+            type=raw,value=${{ matrix.lane }}-latest
             type=raw,value=${{ matrix.lane }}-${{ github.sha }}
 
       - name: Build and push Docker image