ci: Replace github context variables with gitea context variables in Docker build workflow.

.gitea/workflows/docker-build.yml

@@ -9,7 +9,7 @@ on:
 
 env:
   REGISTRY: git.almazlar.com
-  OWNER: ${{ github.repository_owner }}
+  OWNER: ${{ gitea.repository_owner }}
 
 jobs:
   build-and-push:
@@ -25,7 +25,7 @@ jobs:
         uses: docker/login-action@v3
         with:
           registry: ${{ env.REGISTRY }}
-          username: ${{ github.actor }}
+          username: ${{ gitea.actor }}
           password: ${{ secrets.ACCESS_TOKEN }}
 
       - name: Extract metadata (tags, labels) for Backend