Update coverage requirement from ==7.5.* to ==7.6.*

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@7.5.0...7.6.0)

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

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

requirements-test.txt

@@ -1,4 +1,4 @@
-coverage == 7.5.*
+coverage == 7.6.*
 mypy == 1.10.*
 pre-commit == 3.5.*
 tox == 4.15.*