bpo-47129: Add more informative messages to f-string syntax errors (32127)

* Add more informative messages to f-string syntax errors

* 📜🤖 Added by blurb_it.

* Fix whitespaces

* Change error message

* Remove the 'else' statement (as sugested in review)

Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>