Fix format in python.

Author: hzhangxyz

examples/main.py

@@ -45,4 +45,4 @@ def callback(candidate: pyds.Rule) -> bool:
     begin = time.time()
     main()
     end = time.time()
-    print(f"Execution time: {end - begin} seconds")
+    print(f"Execution time: {end - begin:.8f} seconds")