As per the MDN article on HTTP caching:
During cache revalidation, if both If-Modified-Since and If-None-Match
are present, then If-None-Match takes precedence for the validator.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Caching
Previously Miniflux would consider a resource unmodified if the
Last-Modified header had not changed, even if the ETag had changed.
With this commit, Miniflux will consider a resource modified if the ETag
header has changed, even if Last-Modified has not.
This fixes Bug 1 in https://rachelbythebay.com/w/2024/06/11/fsr/
