Bump coverage from 6.2 to 6.3 in /compilesketches

Bumps [coverage](https://github.com/nedbat/coveragepy) from 6.2 to 6.3.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@6.2...6.3)

---
updated-dependencies:
- dependency-name: coverage
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

compilesketches/tests/requirements.txt

@@ -1,4 +1,4 @@
 --requirement ../requirements.txt
-coverage==6.2
+coverage==6.3
 pytest==6.2.5
 pytest-mock==3.6.1