Log Message:
py-immutabledict: updated to 4.1.0

Version 4.1.0

Do not store cached hash value when pickling.

Version 4.0.0

Replace __init__ by __new__.
Add explicit items()/keys()/values() methods to speedup these methods.
Add set/delete/update functions.
Add documentation at immutabledict.corenting.fr

Version 3.0.0

copy() (breaking change): remove the option to pass keyword arguments (which \ 
were present as key/value pairs in the copy). Now the method doesn't take any \ 
arguments (it behaves the same as a normal dict).
Python versions: drop Python 3.7 support
Typing: fixes
Make the key covariant.
Fix key/value typing missing for ImmutableOrderedDict