fix(@astrojs/rss): revert incorrect Content-Type header applied for RSS XML file

[SapphicMoe]

Changes

This fixes an issue where the RSS XML file generated by @astrojs/rss is displayed in plaintext due to a faulty Content-Type header by reverting the #12644 pull request.

For more information, you can view the #12828 issue that I filed.

Example screenshots

Before (current, Content-Type header is set to application/rss+xml; charset=utf-8 since [email protected])

After (manually overriding the Content-Type header to application/xml which was the value used by @astrojs/rss before the PR change)

Testing

A reproducible example can be found here: https://codesandbox.io/p/devbox/kind-hugle-27v5l?on=codesandbox

Or, if you want to reproduce it yourself:

• Go to https://astro.new and find the Blog template
• Open the Blog template in CodeSandbox
• Visit the /rss.xml RSS XML page

You should see the XML page being displayed in plaintext.

Reproducible example screenshot for the "Blog" Template in CodeSandbox