Quote the groups column so members can be created on MySQL 8

"groups" is a reserved word in MySQL 8 but not in MariaDB, so the
unquoted insert and update failed only there.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/Import/MemberResolver.php

@@ -64,7 +64,8 @@ class MemberResolver
                 'dateAdded' => time(),
                 'firstname' => '',
                 'lastname' => $name,
-                'groups' => serialize($groupId > 0 ? [(string) $groupId] : []),
+                // „groups“ ist in MySQL 8 ein reserviertes Wort und muss gequotet werden
+                '`groups`' => serialize($groupId > 0 ? [(string) $groupId] : []),
             ]);
 
             $id = (int) $this->connection->lastInsertId();
@@ -105,6 +106,6 @@ class MemberResolver
         }
 
         $groups[] = (string) $groupId;
-        $this->connection->update('tl_member', ['groups' => serialize(array_values($groups)), 'tstamp' => time()], ['id' => $memberId]);
+        $this->connection->update('tl_member', ['`groups`' => serialize(array_values($groups)), 'tstamp' => time()], ['id' => $memberId]);
     }
 }