fix: add platform variable for credentials workflow

.github/workflows/push-credentials-image.yaml

@@ -9,6 +9,13 @@ on:
   schedule:
     - cron: "0 4 * * 1-5"  # UTC Time
 
+
+#  Added for testing purposes. Will remove once the PR is finalised
+  pull_request:
+    branches:
+      - '**'
+
+
 jobs:
   build-and-push-image:
     runs-on: ubuntu-latest
@@ -43,6 +50,7 @@ jobs:
           push: true
           target: dev
           tags: edxops/credentials-dev:${{ steps.get-tag-name.outputs.result }}
+          platforms: linux/amd64,linux/arm64
 
       - name: Send failure notification
         if: failure()