🔥 remove 3.6 test on macos because macOS lacks of 3.6 support

Author: chfw

.github/workflows/tests.yml

@@ -9,6 +9,9 @@ jobs:
         matrix:
             python-version: [3.6, 3.7, 3.8, 3.9]
             os: [macOs-latest, ubuntu-latest, windows-latest]
+            exclude:
+              - os: macos-latest
+               python-version: 3.6
 
     runs-on:  ${{ matrix.os }}
     name: run tests