Changelogs

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* Removed support for Python 2.7, 3.4 and 3.5
* Added support for Python 3.9
* Getting proper changelogs for beautifulsoup4 PyPi package again
* Getting proper changelogs for synapse PyPi package again
* Stopped using bumpversion
* Updated PyPi map.txt to reflect different packages changelogs location changes
* Fixed bug while processing domain-only URLs (155)

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* Added a pypi/map.txt file to add custom URLS more easily
* Added a bunch of custom URLS:
- pytest-flake8
- cornice.ext.swagger
- python-social-core
- python-social-auth
- cx-oracle
- plotnine
- django-hijack
- pyinvoke
- gitpython
- python-memcached
- appenlight-client

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* Added a bunch of custom parser:
- robozilla
- websocket-client
- pep8-naming
- py-trello
- synapse
- django-haystack
- libsass
- lazy-object-proxy

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* Added a bunch of custom parser:
- flake8
- pyyaml
- six
- factory-boy
- jinja2
- docutils
- sphinx-rtd-theme
- whitenoise
- numpy
- beautifulsoup4
- mccabe
- django-braces
- alabaster
- cffi
- django-coverage-plugin
- newrelic
- pandas
- twine
- pep8-naming
- django-storages-redux
- pbr

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* The changelog finder now checks repo URLs if they contain the given project name. This should
make it easier to identify false changelogs.
* Fixed a couple of internal errors on edge cases.
* Added custom parsers for:
- graphene
- beautifulsoup4

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* Added support for GitHub release pages
* Added experimental support for git commit log parsing