chore(deps-dev): bump coverage from 5.5 to 6.0

Bumps [coverage](https://github.com/nedbat/coveragepy) from 5.5 to 6.0.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@coverage-5.5...6.0)

---
updated-dependencies:
- dependency-name: coverage
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Diff for: poetry.lock

@@ -29,7 +29,7 @@ pydantic = {version = "^1.8.2", optional = true }
 email-validator = {version = "*", optional = true }
 
 [tool.poetry.dev-dependencies]
-coverage = {extras = ["toml"], version = "^5.5"}
+coverage = {extras = ["toml"], version = "^6.0"}
 pytest = "^6.2.5"
 black = "^20.8b1"
 flake8 = "^3.9.0"