Bump diesel from 2.1.4 to 2.1.5

Bumps [diesel](https://github.com/diesel-rs/diesel) from 2.1.4 to 2.1.5.
- [Release notes](https://github.com/diesel-rs/diesel/releases)
- [Changelog](https://github.com/diesel-rs/diesel/blob/v2.1.5/CHANGELOG.md)
- [Commits](diesel-rs/diesel@v2.1.4...v2.1.5)

---
updated-dependencies:
- dependency-name: diesel
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

Cargo.lock

@@ -16,7 +16,7 @@ actix-cors = "0.6.5"
 actix-web-httpauth = "0.8.1"
 env_logger = "0.10.2"
 structopt = "0.3.26"
-diesel = { version = "2.0.3", features = ["sqlite", "r2d2"] }
+diesel = { version = "2.1.5", features = ["sqlite", "r2d2"] }
 diesel_migrations = "2.1.0"
 libsqlite3-sys = { version = "0.27.0", features = ["bundled"] }
 serde = "1.0.197"