added checkout of head branch if PR

Author: tannermpeterson

.github/workflows/dev-test.yaml

@@ -41,6 +41,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v2
         with:
+          ref: ${{ github.head_ref }}
           fetch-depth: 1
 
       - name: Set up Python
@@ -106,6 +107,12 @@ jobs:
           name: codecov-umbrella
           fail_ci_if_error: true
 
+      # - name: Checkout head branch (if Pull Request)
+      #   if: matrix.os == 'ubuntu-latest' && matrix.python-version == 3.7 && github.event_name == 'pull_request'
+      #   run: |
+      #     git fetch origin $GITHUB_HEAD_REF
+      #     git checkout $GITHUB_HEAD_REF
+
       - name: Run prerelease to check packaging compatibilty
         if: matrix.os == 'ubuntu-latest' && matrix.python-version == 3.7
         run: prerelease --no-input