gitignore: Add coverage.json to ignore list

- Excluded `coverage.json` from version control to avoid tracking
  local coverage report artifacts.

Assisted-by: Codex

Author: datalogics-kam

.gitignore

@@ -454,3 +454,4 @@ $RECYCLE.BIN/
 
 !pyrightconfig.json
 /coverage/
+/coverage.json