[hailctl] fix parsing in hailctl hdinsight start (#14110)

CHANGELOG: Fix `hailctl hdinsight start`, which has been broken since
0.2.118.

The shift to typer/click accidentally converted this parameter from a
string to an int.

hail/python/hailtop/hailctl/hdinsight/start.py

@@ -69,7 +69,7 @@ def start(
         '--location',
         location,
         '--workernode-count',
-        num_workers,
+        str(num_workers),
         '--ssh-password',
         sshuser_password,
         '--ssh-user',