gh-129726: Break gzip.GzipFile reference loop (#130055)

A reference loop was resulting in the `fileobj` held by the `GzipFile`
being closed before the `GzipFile`.

The issue started with gh-89550 in 3.12, but was hidden in most cases
until 3.13 when gh-62948 made it more visible.

Lib/gzip.py

@@ -5,11 +5,15 @@ but random access is not allowed."""
 
 # based on Andrew Kuchling's minigzip.py distributed with the zlib module
 
-import struct, sys, time, os
-import zlib
+import _compression
 import builtins
 import io
-import _compression
+import os
+import struct
+import sys
+import time
+import weakref
+import zlib
 
 __all__ = ["BadGzipFile", "GzipFile", "open", "compress", "decompress"]
 
@@ -125,10 +129,13 @@ class BadGzipFile(OSError):
 class _WriteBufferStream(io.RawIOBase):
     """Minimal object to pass WriteBuffer flushes into GzipFile"""
     def __init__(self, gzip_file):
-        self.gzip_file = gzip_file
+        self.gzip_file = weakref.ref(gzip_file)
 
     def write(self, data):
-        return self.gzip_file._write_raw(data)
+        gzip_file = self.gzip_file()
+        if gzip_file is None:
+            raise RuntimeError("lost gzip_file")
+        return gzip_file._write_raw(data)
 
     def seekable(self):
         return False