fix(tests): Fix exception on copying frame.f_locals (Python 3.13)

Starting from Python 3.13, `frame.f_locals` is not `dict` anymore, but
`FrameLocalsProxy`, that cannot be copied using `copy.copy()`. In Python
3.13 and later, it should be copied using a method `.copy()`. The new way
of copying works the same as the old one for versions of Python prior to
3.13, according to the documentation (both copying methods produce a
shallow copy).

See:
https://peps.python.org/pep-0667/
python/cpython#118921
python/cpython#118923
https://docs.python.org/3.13/whatsnew/3.13.html#porting-to-python-3-13
https://docs.python.org/3/library/copy.html

sentry_sdk/utils.py

@@ -11,7 +11,6 @@
 import threading
 import time
 from collections import namedtuple
-from copy import copy
 from datetime import datetime
 from decimal import Decimal
 from functools import partial, partialmethod, wraps
@@ -618,7 +617,7 @@ def serialize_frame(
         )
 
     if include_local_variables:
-        rv["vars"] = copy(frame.f_locals)
+        rv["vars"] = frame.f_locals.copy()
 
     return rv