chore(ci): drop 3.6 from workflows (#1395)

Author: heitorlessa

.github/workflows/python_build.yml

@@ -26,7 +26,7 @@ jobs:
     strategy:
       max-parallel: 4
       matrix:
-        python-version: [3.6, 3.7, 3.8, 3.9]
+        python-version: [3.7, 3.8, 3.9]
     env:
       OS: ${{ matrix.os }}
       PYTHON: ${{ matrix.python-version }}