Made sure that port 9090 could not be randomly selected.

tests/step_defs/server.py

@@ -30,7 +30,7 @@ class Server:
     @property
     def port(self):
         """Get the port of the server."""
-        port = 9090
+        port = "9090"
         if "MTT_PORT" in self.env:
             port = self.env["MTT_PORT"]
         return port
@@ -68,6 +68,7 @@ class Server:
 
     def set_safe_port(self):
         """Set the server port to something not being used."""
+        while self.port == "9090":
             sock = socket()
             sock.bind((self.address, 0))
             self.port = sock.getsockname()[1]