fix(types): typecast ldap options due to wrong types in ldapjs

The provided types by ldapauth-fork are re-exported from ldapjs. ldapjs
is unmaintained by now but since their last update, the
ConnectionOptions type seems to not contain the mandatory parameter
`url` anymore. Therefore this typecast is needed.

Signed-off-by: Erik Michelson <github@erik.michelson.eu>

backend/src/identity/ldap/ldap.service.ts

@@ -72,7 +72,7 @@ export class LdapService {
         tlsOptions: {
           ca: ldapConfig.tlsCaCerts,
         },
-      });
+      } as LdapAuth.Options);
 
       auth.once('error', (error: string | Error) => {
         const exception = this.getLdapException(username, error);