fix(dav): return 405 when collection already exists

See https://datatracker.ietf.org/doc/html/rfc4918#section-9.3.1

SoObjects/SOGo/SOGoObject.m

@@ -413,7 +413,7 @@
   davPrivileges = [NSMutableArray array];
 
   privileges = [[webdavAclManager davPermissionsForRoles: roles
-				  onObject: self] objectEnumerator];
+                                                onObject: self] objectEnumerator];
   while ((privilege = [privileges nextObject]))
     [davPrivileges addObject: davElementWithContent (@"privilege", XMLNS_WEBDAV,
 						     privilege)];