TD-590 Add minimums for passwords

[tom-reinders]

I got an error because the password only had lower and upper case letters.

╷
│ Error: "administrator_password" must contain characters from three of the categories – uppercase letters, lowercase letters, numbers and non-alphanumeric characters, got ### REDACTED PASSWORD THAT ONLY HAS LOWER AND UPPERCASE LETTERS ###
│ 
│   with azurerm_mysql_flexible_server.mysql_flexible_server,
│   on main.tf line 31, in resource "azurerm_mysql_flexible_server" "mysql_flexible_server":
│   31:   administrator_password = random_password.mysql_admin_password.result
│ 
╵