Update bounties page with new preferred bounty payment service

[Zadeis]

Describe the bug
The previously used bug bounty payment service bountysource is no longer functional and hasn't been functional since approximately May 2024. This prevents supports from funding specific functionality or bug/issue resolution. Currently this site/service is still provided on the bounties page.

Expected behavior/changes
Have the docs list/show the preferred bounty service to be used by both developers and supporters.

Additional context
The location of the page is provided below.
docs/development/bounties.md

[gouchi]

We will have to check if perhaps polar.sh could fit for our use case.

[nabby27]

Hi! You can create bounties on Opire. It integrates with GitHub, but you can always put bounties from the dashboard if you don't want to install the bot. Also, you don't pay until someone claims the bounty with a PR, we don't hold any funds.

PS: I'm the co-founder, so if you need anything, feel free to contact me.