chore: drop python 3.6 for cibuildwheel driver

This drops python 3.6 for cibuildwheel.
Building python 3.6 packages is still supported.

unit_test/oci_container_test.py

@@ -83,7 +83,7 @@ def test_container_removed(container_engine):
             shell=True,
             check=True,
             stdout=subprocess.PIPE,
-            universal_newlines=True,
+            text=True,
         ).stdout
         assert container.name is not None
         assert container.name in docker_containers_listing
@@ -94,7 +94,7 @@ def test_container_removed(container_engine):
         shell=True,
         check=True,
         stdout=subprocess.PIPE,
-        universal_newlines=True,
+        text=True,
     ).stdout
     assert old_container_name not in docker_containers_listing