fix: exclude assigned issues from good first issue search

[jahnu-patowary]

What does this PR do?

Adds no:assignee to the GitHub search query in extract_issues_by_user so that issues which are already assigned are excluded from the "good first issue" listing. Also added a test verifying the query construction includes no:assignee.

Related Issue

Fixes #131

Checklist

• [ x ] I read the CONTRIBUTING.md
• [ x ] I ran the project locally and tested my changes
• [ x ] I verified my changes are working as expected
• [ x ] This PR description is written by me, not by AI

[jahnu-patowary]

@drkrillo This is ready for review — all checks are passing. Let me know if you'd like any changes.

[drkrillo]

this files shouldn't be puhed to the repo

[drkrillo]

this files shouldn't be puhed to the repo

[drkrillo]

Hi @jahnu-patowary !!

Thank you very much :) The code looks good and the test, too.

One blocker: we need to leave out those two files (t --cov=app --cov-report=term-missing python -m pytest --cov=app --cov-report=term-missing and t --cov=app --cov-report=term-missingq) from the PR. they are being commited, and we don't need themin the repo. That's it. Then, we are good to merge.

One small comment, but not a blocker: there are some trailing spaces in the blank lines and in the assert. Probably this should be handleded automatically with a linter and we should have a step in the workflow pipeline that checks this. ruff could be an option.... just thinking out loud.

You have created an issue before, so if you are interested, it would be really great if you would like to open an issue for those cases.... there could be two issues: one for the installing the linter and one for the workflow check step. By no means an obligation, but maybe you are interested. Let me know and we can discuss more about it if you like :)