Update mysql_async to 0.31 and prepare 0.2.2 release

Author: weiznich

CHANGELOG.md

@@ -4,6 +4,10 @@ All user visible changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/), as described
 for Rust libraries in [RFC #1105](https://github.com/rust-lang/rfcs/blob/master/text/1105-api-evolution.md)
 
+## [0.2.2] - 2023-04-14
+
+* Dependency updates for `mysql-async` to allow newer versions
+
 ## [0.2.1] - 2023-03-08
 
 * Dependency updates for `mobc` and `mysql-async` to allow newer versions as well