Upgrade quopri from Python 3.14.0 (#6852)

Upgrades the `quopri` module from Python 3.14.0 as part of the ongoing
standard library update effort.

## Changes

- Updated `Lib/quopri.py` from CPython v3.14.0
  - Removed shebang line
  - Changed file mode from executable to regular file
- No functional changes to the module

Lib/quopri.py

@@ -1,5 +1,3 @@
-#! /usr/bin/env python3
-
 """Conversions to/from quoted-printable transport encoding as per RFC 1521."""
 
 # (Dec 1991 version).