Bump clap from 2.34.0 to 3.1.18 (#2824)

* Bump clap from 2.34.0 to 3.1.18

Bumps [clap](https://github.com/clap-rs/clap) from 2.34.0 to 3.1.18.
- [Release notes](https://github.com/clap-rs/clap/releases)
- [Changelog](https://github.com/clap-rs/clap/blob/master/CHANGELOG.md)
- [Commits](https://github.com/clap-rs/clap/compare/v2.34.0...v3.1.18)

---
updated-dependencies:
- dependency-name: clap
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

* update taskchampion-sync-server for clap 3.x

* bump MSRV to 1.54 for extended_key_value_attributes required by clap

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Dustin J. Mitchell <dustin@v.igoro.us>

rust/sync-server/Cargo.toml

@@ -15,7 +15,7 @@ thiserror = "1.0"
 futures = "^0.3.8"
 serde = "^1.0.125"
 serde_json = "^1.0"
-clap = "^2.33.0"
+clap = "^3.1.18"
 log = "^0.4.17"
 env_logger = "^0.9.0"
 rusqlite = { version = "0.27", features = ["bundled"] }