ci: remove ARM64 platform to speed up builds

ARM64 builds take significantly longer and are not needed for current use case.
Can be re-enabled later if ARM support is required.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: MatteoMori

.github/workflows/build-and-push.yaml

@@ -74,7 +74,7 @@ jobs:
           labels: ${{ steps.meta.outputs.labels }}
           cache-from: type=gha
           cache-to: type=gha,mode=max
-          platforms: linux/amd64,linux/arm64
+          platforms: linux/amd64
 
       - name: Generate artifact attestation
         if: github.event_name != 'pull_request'