Update cachetools requirement from <5,>=4.1 to >=4.1,<6

Updates the requirements on [cachetools](https://github.com/tkem/cachetools) to permit the latest version.
- [Changelog](https://github.com/tkem/cachetools/blob/master/CHANGELOG.rst)
- [Commits](tkem/cachetools@v4.1.0...v5.5.0)

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

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

pyproject.toml

@@ -27,7 +27,7 @@ classifiers = [
 
 dependencies = [
     "blinker>=1.4,<2",
-    "cachetools>=4.1,<5",
+    "cachetools>=4.1,<6",
     "debts>=0.5,<1",
     "email_validator>=1.0,<3",
     "Flask>=2,<4",