Fixes using uv pip

Author: jasonb5

.github/workflows/testing.yml

@@ -134,9 +134,10 @@ jobs:
           CIME_DRIVER: "nuopc"
           CIME_TEST_PLATFORM: "ubuntu-latest"
           SKIP_ENTRYPOINT: "true"
+          UV_SYSTEM_PYTHON: 1 
         run: |
           # manually run the entrypoint
-          SKIP_ENTRYPOINT="true" source /entrypoint.sh
+          source /entrypoint.sh
 
           uv pip install -r test-requirements.txt
           uv pip install pytest pytest-cov
@@ -224,9 +225,10 @@ jobs:
           CIME_DRIVER: ${{ matrix.driver }}
           CIME_TEST_PLATFORM: ubuntu-latest
           SKIP_ENTRYPOINT: "true"
+          UV_SYSTEM_PYTHON: 1
         run: |
           # manually run the entrypoint
-          SKIP_ENTRYPOINT=true source /entrypoint.sh
+          source /entrypoint.sh
 
           uv pip install -r test-requirements.txt
           uv pip install pytest pytest-cov