Merge branch 'promote' of github.com:zilder/testgres into promote

Author: zilder

testgres/node.py

@@ -712,7 +712,7 @@ def promote(self, dbname=None, username=None):
 
         # for versions below 10 `promote` is asynchronous so we need to wait
         # until it actually becomes writable
-        if not pg_version_ge("10"):
+        if self._pg_version < '10':
             check_query = "SHOW transaction_read_only"
 
             self.poll_query_until(