💚 Add dependencies caching to GH action

.github/workflows/lint.yml

@@ -14,11 +14,21 @@ jobs:
       uses: actions/setup-python@v1
       with:
         python-version: 3.8
-    - name: Install dependencies
+    - name: Install poetry
       run: |
         python -m pip install --upgrade pip
         pip install poetry>=1.0.0
         poetry config virtualenvs.create false
+        poetry config cache-dir ~/.cache
+    - uses: actions/cache@v1
+      name: Cache
+	  id: cache
+      with:
+        path: ~/.cache
+        key: ${{ runner.os }}-poetry-${{ hashFiles('**/poetry.lock') }}
+    - name: Install dependencies
+      if: steps.cache.outputs.cache-hit != 'true'
+      run: |
         poetry install
     - name: Lint with black
       run: |