Try to force Python x64 on Windows pytest-pipenv

It was using the 32-bit x86 Python instead of the 64-bit x86-64
Python on Windows in the `pytest-pipenv` job, which was never
intended and also caused failures in 3.10, 3.11, 3.12, and 3.13
(during an attempt to build a dependency).

Author: EliahKagan

.github/workflows/test.yml

@@ -131,10 +131,18 @@ jobs:
               -pyver=${{ matrix.python-version }} Pipfile
 
       - name: Set up Python
+        if: matrix.os != 'windows-latest'
         uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
 
+      - name: Set up Python
+        if: matrix.os == 'windows-latest'
+        uses: actions/setup-python@v5
+        with:
+          architecture: x64
+          python-version: ${{ matrix.python-version }}
+
       - name: Upgrade PyPA packages
         run: python -m pip install -U pip setuptools wheel