textproc/py-nltk: update to 3.4.1

Changelog:
+ Add chomsky_normal_form for CFGs
+ Add meteor score
+ Add minimum edit/Levenshtein distance based alignment function
+ Allow access to collocation list via text.collocation_list()
+ Support corenlp server options
+ Drop support for Python 3.4
+ Other minor fixes

PR: 237583
Approved by: demon (maintainer)