Added ninja to known list (#3050)

## Changes
Added `ninja` to known list 

### Linked issues
Partly resolve #1931

Author: pritishpai

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

@@ -11647,6 +11647,9 @@
     "neuralforecast.tsdataset": [],
     "neuralforecast.utils": []
   },
+  "ninja": {
+    "ninja": []
+  },
   "nltk": {
     "nltk": [],
     "nltk.app": [],