fix(rss/atom): sanitize enclosure URLs containing &

[chick-p]

Fixes #227.

[jpmonette]

@chick-p Thanks for the contribution. Could you provide some simple tests for this please?

[Greenheart]

@chick-p I can't edit the git branch directly, but here are some ideas for minimal tests:

The example from the issue could be added as two new test cases - one for RSS and another for Atom:

Invalid:

<enclosure url="https://example.com/hello&world.png" />

Should be sanitized into this:

<enclosure url="https://example.com/hello&amp;world.png" />

These examples could be wrapped in minimal XML and RSS files to represent full test cases.

• Test URL sanitization for RSS
• Test URL sanitization for Atom

[chick-p]

@jpmonette @Greenheart
Thank you for the suggestion!
I've added tests to ensure that enclosure URLs containing & are properly sanitized in both RSS and Atom outputs.
If you have any other feedback or requests, please let me know.

[Greenheart]

Thanks for adding the tests! This looks good :)