run tests on 3.6, 3.7 and 3.8

.github/workflows/ci.yml

@@ -44,15 +44,18 @@ jobs:
   test:
     name: Tests
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: [3.6, 3.7, 3.8]
 
     steps:
     - name: Checkout git repository
       uses: actions/checkout@v2
 
-    - name: Set up Python 3.7
+    - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v1
       with:
-        python-version: 3.7
+        python-version: ${{ matrix.python-version }}
 
     - name: Install poetry
       uses: Gr1N/setup-poetry@v1
@@ -61,8 +64,8 @@ jobs:
       uses: actions/cache@v1
       with:
         path: ~/.cache/pypoetry/virtualenvs
-        key: ${{ runner.os }}-poetry-3.7-${{ hashFiles('**/poetry.lock') }}
-        restore-keys: ${{ runner.os }}-poetry-3.7
+        key: ${{ runner.os }}-poetry-${{ matrix.python-version }}-${{ hashFiles('**/poetry.lock') }}
+        restore-keys: ${{ runner.os }}-poetry-${{ matrix.python-version }}
 
     - name: Install dependencies
       run: poetry install