[DEP] Remove dill dependency

[bact]

Currently, pythainlp.tag.perceptron is the only submodule that uses dill.

dill is an extended version of pickle.

Looks like we currently use a very basic functionality of of serialization that the standard pickle may able to handle and there's no need for dill.

pythainlp/pythainlp/tag/perceptron.py

Line 19 in d2b67e0

model = dill.load(fh)

Propose to investigate more and see if we can move from dill to pickle and reduce the number of mandatory dependencies by one.

[wannaphong]

NLTK is used code from A Good Part-of-Speech Tagger in about 200 Lines of Python https://explosion.ai/blog/part-of-speech-pos-tagger-in-python

NLTK https://www.nltk.org/_modules/nltk/tag/perceptron.html