Remove old pylint comment about the SDK

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

src/frequenz/repo/config/nox/default.py

@@ -39,7 +39,6 @@
         "--install-types",
         "--non-interactive",
     ],
-    # SDK: pylint "--extension-pkg-whitelist=pydantic"
     pytest=[
         "-W=all",
         "-vv",