refactor: update mysql client to mysql2

[McSneaky]

Proposed changes

Updating to mysql2 allows to use MySQL 8 and above. There's been issue opened in mysql repo, but seems like it's stale mysqljs/mysql#1959

mysql2 is API compatible with mysql so there really shouldn't be any breaking changes

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• I have read the CONTRIBUTING doc
• Lint and unit tests pass locally with my changes (Used GH online edit, didn't run tests)
• I have added tests that prove my fix is effective or that my feature works.
• I have added necessary documentation (if appropriate) - Update to mysql2 v5-docs#179

Further comments

[thetutlage]

Danke