Bump diskcache from 4.1.0 to 5.0.2 in /cvat/requirements (#2145)

Bumps [diskcache](https://github.com/grantjenks/python-diskcache) from 4.1.0 to 5.0.2.
- [Release notes](https://github.com/grantjenks/python-diskcache/releases)
- [Commits](https://github.com/grantjenks/python-diskcache/compare/v4.1.0...v5.0.2)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

cvat/requirements/base.txt

@@ -44,4 +44,4 @@ tensorflow==2.2.0 # Optional requirement of Datumaro
 # The package is used by pyunpack as a command line tool to support multiple
 # archives. Don't use as a python module because it has GPL license.
 patool==1.12
-diskcache==4.1.0
+diskcache==5.0.2