remove macos for now and add activate venv step

Author: dpgraham4401

.github/workflows/CI.yml

@@ -17,7 +17,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ ubuntu-latest, macos-latest ]
+        os: [ ubuntu-latest ]
     runs-on: ${{ matrix.os }}
 
     steps:
@@ -55,6 +55,9 @@ jobs:
         with:
           cache-dependency-glob: "**/pyproject.toml"
 
+      - name: 'Activate virtual environment'
+        run: . .venv/bin/activate
+
       - name: Install dependencies
         run: uv sync --locked --all-extras --dev