[CI] Use setup-python action pip cache

Replace custom pip cache that didn't work correctly on Windows with
option to use pip cache in setup-python action

.github/workflows/ci.yml

@@ -24,16 +24,8 @@ jobs:
         uses: actions/setup-python@v2
         with:
           python-version: ${{ matrix.python-version }}
-
-      - name: Cache pip
-        uses: actions/cache@v2
-        with:
-          path: ~/.cache/pip
-          # Look to see if there is a cache hit for the corresponding requirements file
-          key: ${{ runner.os }}-pip-${{ hashFiles('tox.ini', 'setup.py', 'requirements*.txt') }}
-          restore-keys: |
-            ${{ runner.os }}-pip-
-            ${{ runner.os }}-
+          cache: "pip"
+          cache-dependency-path: "requirements*.txt"
 
       - name: Sets env var for security
         if: (github.event_name == 'pull_request' && contains(github.event.pull_request.body, 'security_test')) || (github.event_name == 'push' && contains(github.event.head_commit.message, 'security_test'))
@@ -88,16 +80,8 @@ jobs:
         uses: actions/setup-python@v2
         with:
           python-version: ${{ matrix.python-version }}
-
-      - name: Cache pip
-        uses: actions/cache@v2
-        with:
-          path: '%LOCALAPPDATA%\pip\Cache'
-          # Look to see if there is a cache hit for the corresponding requirements file
-          key: ${{ runner.os }}-pip-${{ hashFiles('tox.ini', 'setup.py', 'requirements*.txt') }}
-          restore-keys: |
-            ${{ runner.os }}-pip-
-            ${{ runner.os }}-
+          cache: "pip"
+          cache-dependency-path: "requirements*.txt"
 
       - name: Install dependencies
         run: |