Sopel-github

This is the first release named `sopel-github`. Previous versions of this plugin
were known as `sopel_modules.github`, and are still available from PyPI for
users running Sopel 7.x or older.

Added:
* Support for inline references to issues/PRs from _any_ repo (125)
* Timestamps in issue, PR, and comment output (126)
* Configurable skipping of short inline issue/PR numbers (137)
* This is to help bot owners deal with e.g. people talking about their `1`
_something_ and the bot posts your project's first issue.

Changed:
* Modernized for newer Sopel versions (110, 138)
* Send version header to GitHub API (122)
* Reworked PR merge status lookup (123)

Fixed:
* Handle directory links, not just files (134)
* Suppress errors for invalid inline issue references (136)

Removed:
* Obsolete `secret` setting (124)

Meta:
* New package name, `sopel-github` (138)
* Sopel 8.0+ now required (138)
* Made optional `:emoji_name:` conversion a setuptools extra (120, 140)
* Install `sopel-github[emojize]` to enable this feature.

Changed:
* Use `emoji` 2.0 API style (119)
* If you installed the `emoji` package and its version is <1.7.0, you will
need to `pip install --upgrade emoji`.
* A future version of sopel-github will make this optional dependency easier
to manage with a setuptools extra.

Fixed:
* Wrong webhook payload attributes used in push handler (117)

Added:
* Special `.gh-repo !clear` syntax to delete a channel's linked repo (112)
* Output relative committer & author date for commit URLs (114)

Changed:
* Prettified `.gh-repo` output (112)

Fixed:
* `NameError` in `.gh version` subcommand ( 111)
* `TypeError` in `.gh-repo` in channel with no linked repository (112)
* Incorrect plural "1 changes" in commit output (113)
* Reduced false-positive Markdown heading detection (115)
* Ignore URI fragments in repo links (116)

Changed:
* No longer attempt to shorten links with shut-down git.io (106)

Fixed:
* Fix some edge cases in excerpted comment bodies (105)
* Clean up some output-formatting code (107)

Fixed:
* Link matching did not allow for underscore (`_`) in repo names (100)

Fixed:
* Regression in handling inline/standalone issue references (99)