ci(github-actions): pre-commit cache

Fixes #1.

Author: m0wer

.github/workflows/tests.yml

@@ -1,7 +1,7 @@
 ---
 name: Tests
 
-on:
+on:  # yamllint disable-line rule:truthy
   push:
   pull_request:
 
@@ -21,11 +21,18 @@ jobs:
         uses: actions/cache@v2
         with:
           path: ~/.cache/pip
-          key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements-dev.txt') }}
+          key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements*.txt') }}
           restore-keys: |
             ${{ runner.os }}-pip-
       - name: Install dependencies
         run: make install
+      - name: Cache pre-commit
+        uses: actions/cache@v2
+        with:
+          path: ~/.cache/pre-commit
+          key: pre-commit-2--${hashFile('.pre-commit-config.yaml')}
+          restore-keys: |
+            pre-commit-2-
       - name: Lint
         run: SKIP=no-commit-to-branch make lint
       - name: Test