Add --check-change option, for pre-commit export hook

[noamraph]

This is required to fix python-poetry/poetry#8512 / #237.

Currently, the poetry-export pre-commit hook returns 0 even when it changes the requirements.txt file. As written here, pre-commit hooks should return a nonzero value when modifying files. This is required in order to make pipelines fail if files are not as expected - in this case, if the requirements.txt file was not updated.

I added a --check-change option, which causes poetry export to return 1 if it changed the output. python-poetry/poetry#8810 in the main poetry repository changes the hook to add the --check-change option.

Note: I didn't add a test yet. If you approve of the approach, I'll happily add a test.

[sonarqubecloud]

Quality Gate passed

The SonarCloud Quality Gate passed, but some issues were introduced.

1 New issue
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

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[noamraph]

I think that this change isn't needed - it turns out that pre-commit checks if the content was changed, and doesn't require a nonzero return code.

See: pre-commit/pre-commit.com#912 (comment)