autotest: correct format string in error path

name is a string, not an integer

Tools/autotest/vehicle_test_suite.py

@@ -13682,7 +13682,7 @@ switch value'''
             n = self.poll_home_position(timeout=120)
             distance = self.get_distance_int(orig, n)
             if distance > 1:
-                raise NotAchievedException("gps type %u misbehaving" % name)
+                raise NotAchievedException(f"gps type {name} misbehaving")
 
     def assert_gps_satellite_count(self, messagename, count):
         m = self.assert_receive_message(messagename)