Update dump_pit.py (#1759)

seperated -> separated

Co-authored-by: Linlang Lv (iSoftStone Information) <v-lvlinlang@microsoft.com>

scripts/dump_pit.py

@@ -3,7 +3,7 @@
 """
 TODO:
 - A more well-designed PIT database is required.
-    - seperated insert, delete, update, query operations are required.
+    - separated insert, delete, update, query operations are required.
 """
 
 import shutil