update github actions due to deprecation warnings (#70)

Author: bh2smith

.github/workflows/pull-request.yaml

@@ -10,7 +10,7 @@ jobs:
       matrix:
         python-version: ["3.7", "3.11"]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v2
         with:
@@ -33,7 +33,7 @@ jobs:
       matrix:
         python-version: ["3.7", "3.11"]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v2
         with: