CI: updated build py versions

Seems Python 3.6 is no longer found.

.github/workflows/main.yml

@@ -23,7 +23,7 @@ jobs:
     
     strategy:
       matrix:
-        python-version: [3.6.x, 3.8.x, 3.10.x, 3.11.x]
+        python-version: [3.7.x, 3.8.x, 3.10.x, 3.11.x]
 
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps: