Try to add a cache for pip on Windows

Author: adamtheturtle

.github/workflows/windows-ci.yml

@@ -29,6 +29,16 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
 
+      - uses: actions/cache@v2
+        with:
+          path: ~\AppData\Local\pip\Cache
+          # This is like the example but we use ``*requirements.txt`` rather
+          # than ``requirements.txt`` because we have multiple requirements
+          # files.
+          key: ${{ runner.os }}-pip-${{ hashFiles('**/*requirements.txt') }}
+          restore-keys: |
+            ${{ runner.os }}-pip-
+
       - name: "Install dependencies"
         run: |
           python -m pip install --upgrade pip setuptools wheel