Set GitHub ci workflow checkout branch ref to 2.0.

.github/workflows/ci.yml

@@ -13,6 +13,8 @@ jobs:
         steps:
             - name: checkout
               uses: actions/checkout@v3
+              with:
+                ref: '2.0'
             - name: Set up Python 3.9
               uses: actions/setup-python@v4
               with:
@@ -33,6 +35,7 @@ jobs:
             - name: "checkout repository"
               uses: actions/checkout@v4
               with:
+                  ref: '2.0'
                   fetch-depth: 0
             - name: Set up Python ${{ matrix.python-version }} (minimum supported python version for deltaCAT is 3.9)
               uses: actions/setup-python@v4
@@ -53,7 +56,7 @@ jobs:
                   python -m pytest -m "not integration" --benchmark-json output.json
             # Download previous benchmark result from cache (if exists)
             - name: Download previous benchmark data
-              uses: actions/cache@v1
+              uses: actions/cache@v4
               with:
                   path: ./cache
                   key: ${{ runner.os }}-benchmark