test: fix flaky test-http2-client-unescaped-path on osx

PR-URL: https://github.com/nodejs/node/pull/14239
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

test/parallel/test-http2-client-unescaped-path.js

@@ -13,7 +13,7 @@ const count = 32;
 server.listen(0, common.mustCall(() => {
   const client = http2.connect(`http://localhost:${server.address().port}`);
 
-  let remaining = count;
+  let remaining = count + 1;
   function maybeClose() {
     if (--remaining === 0) {
       server.close();