fix(ci): remove GHA cache-from/cache-to (CAR-1357)

The build-and-push job fails post-merge of CAR-1356's REGISTRY_TOKEN
fix: the cache-from/cache-to: type=gha backend does not exist on
Gitea. Build itself succeeds, but the post-build cache export step
fails with 'invalid character N looking for beginning of value' and
cascades to skipping the 'Push Docker image' step.

Per CAR-1362, drop cache-from and cache-to entirely from both the
Build Docker image and Push Docker image steps. Matches the proven-
green cartsnitch/auth/ci.yml pattern (dev branch HEAD has no cache
config and builds-and-pushes in one shot).

Refs: CAR-1356, CAR-1330, CAR-1357.

Co-authored-by: Paperclip <noreply@paperclip.ing>

.gitea/workflows/ci.yml

@@ -140,8 +140,6 @@ jobs:
           labels: ${{ steps.meta.outputs.labels }}
           build-args: |
             APT_CACHE_BUST=${{ github.run_id }}
-          cache-from: type=gha
-          cache-to: type=gha,mode=max
 
       - name: Scan api image for vulnerabilities
         uses: anchore/scan-action@v5
@@ -168,7 +166,6 @@ jobs:
           labels: ${{ steps.meta.outputs.labels }}
           build-args: |
             APT_CACHE_BUST=${{ github.run_id }}
-          cache-from: type=gha
 
       - name: Create git tag
         if: github.event_name == 'push' && github.ref == 'refs/heads/main'