Bump gitdb/ext/smmap from 8f82e6c to c6b53d3

Bumps [gitdb/ext/smmap](https://github.com/gitpython-developers/smmap) from `8f82e6c` to `c6b53d3`.
- [Release notes](https://github.com/gitpython-developers/smmap/releases)
- [Commits](gitpython-developers/smmap@8f82e6c...c6b53d3)

---
updated-dependencies:
- dependency-name: gitdb/ext/smmap
  dependency-version: c6b53d35deb82a38d5d07ca7712c1334a7a10c10
  dependency-type: direct:production
...

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

Author: dependabot[bot]