OO-4308: increase default user name max. length to 64

src/main/resources/serviceconfig/olat.properties

@@ -222,7 +222,7 @@ login.using.username.or.email.enabled=true
 
 # Regex to validate username of new users. If yo change this property,
 # Make sure to change the translation of $org.olat.user\:form.checkUsername accordingly.
-username.regex=[0-9a-z\\.\\-@_]{4,32}
+username.regex=[0-9a-z\\.\\-@_]{4,64}
 
 # permit users to change their own passwords
 # (if you set this to false, nobody can can change their pws!)