Fix macOS workflow (#213)

* Add virtualenv

* Change python version

* Fix

* Change to pytest?

* Fix missing source (hopefully)

.github/workflows/macOS.yaml

@@ -10,7 +10,7 @@ jobs:
     runs-on: macos-latest
     strategy:
         matrix:
-            python-version: ["3.7.17", "3.12.0"]
+            python-version: ["3.7", "3.12"]
     name: pytest-macos-python-${{ matrix.python-version }}
     steps:
       - name: Checkout
@@ -28,12 +28,15 @@ jobs:
         run: |
           rm -f /usr/local/bin/2to3* /usr/local/bin/python3* /usr/local/bin/idle3* \
           /usr/local/bin/pydoc3* # Homebrew will fail if these exist
-          brew install gnu-time coreutils diffutils dpkg ghostscript texlive
+          brew install gnu-time coreutils diffutils dpkg ghostscript texlive virtualenv
       - name: Install Python dependencies
         run: |
-          python3 -m pip install .[tests]
+          python3 -m venv .venv
+          source .venv/bin/activate
+          pip install .[tests]
       - name: Run pytest
         env:
           PYTEST_ADDOPTS: "--color=yes"
         run: |
-          python3 -m pytest -v --time-tool time
+          source .venv/bin/activate
+          pytest -v --time-tool time