ubuntu20: libvips-dev provided by ppa:tonimelisma/ppa is not available anymore

[mrngm]

Since a couple of months (we noticed it early April 2023), the PPA mentioned in the README is not accessible anymore.

I'm not sure if there are plans to revive the PPA (provided by @tonimelisma at the time), but it might be a good idea to let the README reflect the current state of this dependency.

[tonimelisma]

Hey @mrngm thanks for the feedback, you're completely correct. I retired the PPA as I didn't see many people using it as new Ubuntu versions were out. Do you still have a need for the old backported libvips packages for Ubuntu?

If so, the Dockerfiles needed for easy building your own dpkgs are here:

https://github.com/tonimelisma/libvips-dev-tonimelisma

I'll remove it from the README

[mrngm]

Hi @tonimelisma we're currently at Ubuntu 20.04, and we irregularly introduce new VMs that need libvips as well for these govips bindings. This LTS is (as far as Ubuntu is concerned) supported until April 2025. I suppose it wouldn't hurt to keep the PPA online during the expected support timeline of the LTS, if it's not too much of a hassle.

From your comment I see that you intend to keep the PPA offline. In that case, we can build the package ourselves using the Dockerfiles you provided.

Thanks for clarifying the README!

[tonimelisma]

Thanks @mrngm - I'm really sorry as I didn't realize people were still using it. Unfortunately there's no easy way to restore the PPA. You'll probably set one up as easy as I would set mine up again so yeah, go ahead and use the Dockerfiles to build the packages. You can also, while you're at it, build newer versions if you will.