Release mergeback 6.2.0

(maint) - Update link to metadata.json

Since MariaDB 10.2.16, the `SET PASSWORD` command stores user passwords
in the `mysql_native_password` plugin `authentication_string` instead of
in the `password` column:

```
+------+-----------+----------+-----------------------+-------------------------------------------+
| user | host      | password | plugin                | authentication_string                     |
+------+-----------+----------+-----------------------+-------------------------------------------+
| root | localhost |          | mysql_native_password | *01396341988BCA5088C3A5DB5D7E434947096D4F |
+------+-----------+----------+-----------------------+-------------------------------------------+
```

The `puppetlabs/mysql` checks the `password` column instead of the
`authentication_string` on all versions of MariaDB, resulting in every
Puppet run attempting to update managed user passwords even when they
haven't changed.

Update the if statement to check the plugin authentication string on
MariaDB 10.2.16 and newer.

(MODULES-7487) Check authentication string for user password on MariaDB 10.2.16+

MySQL 8 compatibility in user management

(MODULES-7857) Support user creation on galera

(MODULES-6923) remove staging module

7.0.0 Release Prep