Back out the things that didn't work

.github/workflows/unit-tests.yml

@@ -27,25 +27,20 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
-    - name: Set up Python 3.12
+    - name: Set up Python 3.8
       uses: actions/setup-python@v4
       with:
-        python-version: "3.12"
+        python-version: "3.8"
     - name: Install dependencies
       run: |
-        python -m venv .venv
-        source .venv/bin/activate
         make requirements
     - name: Build packages
       run: |
-        source .venv/bin/activate
         make package
     - name: Run tests
       run: |
-        source .venv/bin/activate
         pip install -e .
         make coverage
     - name: Check docs
       run: |
-        source .venv/bin/activate
         make docs