fix fast/slow test selection logic

.github/workflows/run-tests.yml

@@ -35,7 +35,10 @@ jobs:
       matrix:
         python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
         os: [ubuntu-latest, windows-latest, macos-13, macos-latest]
-        extras: ["test-full"]
+        include:
+          # Only run slow tests on the latest version of Python
+          - python-version: "3.12"
+            slow: true
     runs-on: ${{ matrix.os }}
 
     steps:
@@ -63,12 +66,8 @@ jobs:
 
     - name: Install Scenic and dependencies
       run: |
-        python -m pip install -e ".[${{ matrix.extras }}]"
+        python -m pip install -e ".[test-full]"
 
-    - name: Run pytest in fast mode
+    - name: Run pytest
       run: |
-        pytest ${{ inputs.options || '--fast --no-graphics' }}
-    
-    - name: Run pytest in full mode
-      if: ${{ (matrix.os == 'windows-latest' || matrix.os == 'macos-13' || matrix.os == 'macos-latest') && matrix.python-version == '3.12' }}
-      run: pytest --no-graphics
+        pytest ${{ inputs.options || (matrix.slow && '--no-graphics' || '--fast --no-graphics') }}