Specify branch for PR artifact storage (#1187)

.github/workflows/main.yml

@@ -147,4 +147,5 @@ jobs:
       with:
         commit: ${{ github.event.pull_request.head.sha }}
         repo-token: ${{ secrets.GITHUB_TOKEN }}
+        artifacts-branch: artifacts
         artifacts: ./firmware-${{ steps.version.outputs.version }}.zip