Update mysql

Changes:

- https://github.com/docker-library/mysql/commit/776073e: Merge pull request https://github.com/docker-library/mysql/pull/710 from infosiftr/permissive
- https://github.com/docker-library/mysql/commit/285fd39: Make arbitrary user work better out-of-the-box

library/mysql

@@ -5,13 +5,13 @@ Maintainers: Tianon Gravi <[email protected]> (@tianon),
 GitRepo: https://github.com/docker-library/mysql.git
 
 Tags: 8.0.21, 8.0, 8, latest
-GitCommit: b0f81a33748561ae4e35a09895b2ad112ff89ba6
+GitCommit: 285fd39122e4b04fbe18e464deb72977df9c6a45
 Directory: 8.0
 
 Tags: 5.7.31, 5.7, 5
-GitCommit: a6b87c55ecdf9426d42ff7814be7e9b1fc33b292
+GitCommit: 285fd39122e4b04fbe18e464deb72977df9c6a45
 Directory: 5.7
 
 Tags: 5.6.49, 5.6
-GitCommit: 3607c86e534658529a638e7616bfc1e02528e667
+GitCommit: 285fd39122e4b04fbe18e464deb72977df9c6a45
 Directory: 5.6