Update mypy requirement from ~=1.5 to ~=1.6

Updates the requirements on [mypy](https://github.com/python/mypy) to permit the latest version.
- [Commits](python/mypy@v1.5.0...v1.6.0)

---
updated-dependencies:
- dependency-name: mypy
  dependency-type: direct:development
...

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

Pipfile

@@ -5,7 +5,7 @@ verify_ssl = true
 
 [dev-packages]
 sphinx = "~=7.2"
-mypy = "~=1.5"
+mypy = "~=1.6"
 yapf = "~=0.40"
 twine = "*"
 matplotlib = "*"