Update mysql Docker tag to v8.1 (PlaytikaOSS#1425)

| datasource | package | from | to  |
| ---------- | ------- | ---- | --- |
| docker     | mysql   | 8.0  | 8.1 |

Co-authored-by: Renovate Bot <[email protected]>

Author: Fameing

embedded-mysql/README.adoc

@@ -18,7 +18,7 @@
 * `embedded.mysql.reuseContainer` `(true|false, default is false)`
 * `embedded.mysql.encoding` `(default is 'utf8mb4')`
 * `embedded.mysql.collation` `(default is 'utf8mb4_unicode_ci')`
-* `embedded.mysql.dockerImage` `(default is 'mysql:8.0')`
+* `embedded.mysql.dockerImage` `(default is 'mysql:8.1')`
 ** Image versions on https://hub.docker.com/_/mysql?tab=tags[dockerhub]
 * `embedded.mysql.waitTimeoutInSeconds` `(default is 60 seconds)`
 * `embedded.mysql.initScriptPath` `(default is null)`