Stop running CI on Python 3.6

Author: vrslev

.github/workflows/main.yml

@@ -10,9 +10,6 @@ jobs:
         - os: ubuntu-latest
           python-version: "3.10"
           jack: jackd2
-        - os: ubuntu-latest
-          python-version: "3.6"
-          jack: jackd2
         - os: ubuntu-latest
           python-version: "3.10"
           jack: jackd1