Add pythainlp.coref

[wannaphong]

What does this changes

Add pythainlp.coref for support Thai Coreference resolution

from pythainlp.coref import coreference_resolution
print(coreference_resolution(["Bill Gates ได้รับวัคซีน COVID-19 เข็มแรกแล้ว ระบุ ผมรู้สึกสบายมาก"]))
# output:
# [
# {'text': 'Bill Gates ได้รับวัคซีน COVID-19 เข็มแรกแล้ว ระบุ ผมรู้สึกสบายมาก', 
# 'clusters_string': [['Bill Gates', 'ผม']], 
# 'clusters': [[(0, 10), (50, 52)]]}
# ]

How this fixes it

Description of how the changes fix the issue.

Fixes #800

Your checklist for this pull request

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• Passed code styles and structures
• Passed code linting checks and unit test

[coveralls]

coverage: 91.562% (+34.6%) from 56.963% when pulling f58d51a on add-coref into 33c5b5a on dev.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

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2 Code Smells

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