FreshRSS doesn't seem to detect the content type of certain feeds

To Reproduce
Steps to reproduce the behavior:

1. Go to the Add Subscription dialog
2. Add this feed https://daily.bandcamp.com/feed/ or https://daily.bandcamp.com/feed/rss.xml
3. The feed will display an error and won't get added

A feed could not be found at https://daily.bandcamp.com/feed/; the status code is 200 and content-type is `` [https://daily.bandcamp.com/feed/]

Expected behavior
A clear and concise description of what you expected to happen.

Add the blog's feed to my account and retrieve its entries.

Screenshots
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Environment information (please complete the following information):

Versión
1.19.0-dev
Performed from the web interface.
FreshRSS is installed on a Raspberry Pi with Debian Buster.