fix(ci): use REGISTRY_TOKEN for build-and-push registry login (CAR-1330)

Unblocks CAR-1132 production deploy. The automatic github.token has no
package/registry write scope; auth's proven-green ci.yml uses
secrets.REGISTRY_TOKEN instead.

cc @cpfarhood

.gitea/workflows/ci.yml

@@ -118,7 +118,7 @@ jobs:
           echo "CalVer tag: $VERSION"
 
       - name: Log in to Gitea Container Registry
-        run: echo "${{ github.token }}" | docker login git.farh.net -u ${{ github.actor }} --password-stdin
+        run: echo "${{ secrets.REGISTRY_TOKEN }}" | docker login git.farh.net -u ${{ github.actor }} --password-stdin
 
       - name: Extract metadata
         id: meta