Deno's cache API does not respect expiry dates.
This meant that feeds were cached much longer than intended.
This PR implments a manual cache handling instead of relying on
Deno's implementation. Relevant issue: https://github.com/denoland/deno/issues/25795
* Add a second promo text to the front.
NRSS does not have enough supporters to break even and thus costs me
quite a bit every month. However, it seems to have a stable and high
user base, most of whom presumably could pay. As earlier, I'd like to
avoid shoving the service behind a paywall - that feels totally wrong
for what this project is supposed to be. This PR introduces another,
shorter link to donations _before_ the episode description in the
hopes of attracting more paid users. Let's see if it works :)
Not the most elegant solution. But it works at the expense of old episodes.
I should think of something better at some point. Left some ideas in the code
for future reference.