chore(deps): bump validator from 0.18.1 to 0.20.0

Bumps [validator](https://github.com/Keats/validator) from 0.18.1 to 0.20.0.
- [Changelog](https://github.com/Keats/validator/blob/master/CHANGELOG.md)
- [Commits](Keats/validator@v0.18.1...v0.20.0)

---
updated-dependencies:
- dependency-name: validator
  dependency-version: 0.20.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

Cargo.lock

@@ -15,7 +15,7 @@ diesel_migrations = "2.3"
 libsqlite3-sys = { version = "0.36", features = ["bundled"] }
 rocket_okapi = { version = "0.9.0", features = ["swagger"] }
 schemars     = { version = "1.2" }
-validator    = { version = "0.18", features = ["derive"] }
+validator    = { version = "0.20", features = ["derive"] }
 
 [profile.release]
 lto           = true   # link-time optimisation — reduces binary size and improves inlining