Fix blank line skipping in read_fwf, issue 22693
- [x] closes #22693 
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Fixes the bug where blank lines are not skipped using read_fwf even when skip_blank_lines is set to true. Override default behaviour in FixedWidthFieldParser.