Update cmd2 requirement from ~=2.1.2 to ~=2.4.3

Updates the requirements on [cmd2](https://github.com/python-cmd2/cmd2) to permit the latest version.
- [Release notes](https://github.com/python-cmd2/cmd2/releases)
- [Changelog](https://github.com/python-cmd2/cmd2/blob/master/CHANGELOG.md)
- [Commits](python-cmd2/cmd2@2.1.2...2.4.3)

---
updated-dependencies:
- dependency-name: cmd2
  dependency-type: direct:production
...

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

requirements.txt

@@ -1,4 +1,4 @@
 setuptools~=68.1.0
 blessed~=1.18.0
-cmd2~=2.1.2
+cmd2~=2.4.3
 pygame~=2.5.1