update gitignore

Author: YaoFANGUK

.gitignore

@@ -350,6 +350,7 @@ $RECYCLE.BIN/
 
 # End of https://www.toptal.com/developers/gitignore/api/intellij+all,python,pycharm+all,macos,windows
 /backend/models/V2/ch_rec/inference.pdiparams
+/backend/models/V4/ch_det/inference.pdiparams
 /output/
 /backend/test.py
 /dylib/