Upgrade pylint to 2.12.2 (pylint-dev#1297)

* Upgrade pylint to 2.12.2

* Default Python in the CI is now python 3.8

* Remove useless suppression for python 3.8

* Disable no-member for false positive with zipimport

Author: Pierre-Sassoulas

astroid/nodes/node_ng.py

@@ -30,6 +30,8 @@
 from astroid.nodes.const import OP_PRECEDENCE
 
 if TYPE_CHECKING:
+    from astroid import nodes
+
     if sys.version_info >= (3, 6, 2):
         from typing import NoReturn
     else: