Fixed typo in known.json (#1899)

Author: nfx

src/databricks/labs/ucx/source_code/known.json

@@ -404,7 +404,7 @@
     "fsspec.utils": []
   },
   "gast": {
-    "gast": [],
+    "gast": []
   },
   "gitdb": {
     "gitdb": []