Update coverage requirement from ~=6.3.3 to ~=6.4 (Pycord-Development…

…#1378)

Updates the requirements on [coverage](https://github.com/nedbat/coveragepy) to permit the latest version.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@6.3.3...6.4)

---
updated-dependencies:
- dependency-name: coverage
  dependency-type: direct:development
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements-dev.txt

@@ -4,4 +4,4 @@ pytest~=7.1.2
 pytest-asyncio~=0.18.3
 # pytest-order~=1.0.1
 mypy~=0.960
-coverage~=6.3.3
+coverage~=6.4