ruff: enable TC — flake8-type-checking (#11368)

## Problem

`TYPE_CHECKING` is used inconsistently across Python tests.

## Summary of changes
- Update `ruff`: 0.7.0 -> 0.11.2
- Enable TC (flake8-type-checking):
https://docs.astral.sh/ruff/rules/#flake8-type-checking-tc
- (auto)fix all new issues

scripts/download_basebackup.py

@@ -8,9 +8,12 @@
 from __future__ import annotations
 
 import argparse
+from typing import TYPE_CHECKING
 
 import psycopg2
-from psycopg2.extensions import connection as PgConnection
+
+if TYPE_CHECKING:
+    from psycopg2.extensions import connection as PgConnection
 
 
 def main(args: argparse.Namespace):