Add data_schema to prettierignore

I'm getting this error when linting locally:

[error] No parser could be inferred for file "find-a-lost-trn/db/data_schema.rb".

We don't need to lint this file anyway, so add it to the ignore list.

.prettierignore

@@ -26,6 +26,7 @@ bin/dev
 data
 db/*.sqlite3
 db/schema.rb
+db/data_schema.rb
 log
 public/assets
 storage