Update pickle.py from 3.14.2 (RustPython#6982)

* Update `_compat_pickle.py` from 3.14.2

* Update `pickle.py` from 3.14.2

* Update pickletools and tests

* Update all other pickle related files

* Make `test_extcall` to use modified doctest checker

Author: ShaharNaveh

Lib/_compat_pickle.py

@@ -22,7 +22,6 @@
     'tkMessageBox': 'tkinter.messagebox',
     'ScrolledText': 'tkinter.scrolledtext',
     'Tkconstants': 'tkinter.constants',
-    'Tix': 'tkinter.tix',
     'ttk': 'tkinter.ttk',
     'Tkinter': 'tkinter',
     'markupbase': '_markupbase',
@@ -257,3 +256,4 @@
 
 for excname in PYTHON3_IMPORTERROR_EXCEPTIONS:
     REVERSE_NAME_MAPPING[('builtins', excname)] = ('exceptions', 'ImportError')
+del excname