fix: parse keywords that end code stream

[qued]

Pull request

Closes 884. A small change so that if no keyword-terminating-pattern is found before the stream is exhausted, the keyword is considered terminated and sent for parsing.

How Has This Been Tested?

Included test that fails before change and succeeds after change. Also see attached document in linked issue for a PDF that is not parsed correctly before the change and is parsed correctly after.

Checklist

• I have read CONTRIBUTING.md.
• I have added a concise human-readable description of the change to CHANGELOG.md.
• I have tested that this fix is effective or that this feature works.
• I have added docstrings to newly created methods and classes.
• I have updated the README.md and the readthedocs documentation. Or verified that this is not necessary.

[pietermarsman]

I flipped the if-else for readability and simplified the test. Ready for merging now.

Thanks for your time and contribution!