Update tbump requirement from ~=6.6.0 to ~=6.7.0

Updates the requirements on [tbump](https://github.com/dmerejkowsky/tbump) to permit the latest version.
- [Release notes](https://github.com/dmerejkowsky/tbump/releases)
- [Changelog](https://github.com/dmerejkowsky/tbump/blob/main/Changelog.rst)
- [Commits](your-tools/tbump@v6.6.0...v6.7.0)

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

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

requirements_test.txt

@@ -3,7 +3,7 @@
 coveralls~=3.3
 coverage~=6.2
 pre-commit~=2.16;python_full_version>="3.6.2"
-tbump~=6.6.0
+tbump~=6.7.0
 pyenchant~=3.2
 pytest-cov~=3.0
 pytest-profiling~=1.7