Merge pull request #263 from aws-amplify/update-test-branch

chore: default staging test branch to 'main' unless specified

Author: jordanvn

.github/actions/setup-samples-staging/action.yml

@@ -34,7 +34,7 @@ runs:
       shell: bash
       working-directory: ./amplify-js-samples-staging
       env:
-        BRANCH: next-geo
+        BRANCH: ${{ github.ref_name }}
       run: |
         if git ls-remote --exit-code --heads origin $BRANCH >/dev/null 2>&1; then
             # Branch exists, checkout and echo success message