Update Arch Linux package URL in installation.rst

[felixonmars]

The old URL returns 404 now.

• I have reviewed the Contributor Guidelines.
• I have reviewed the Code of Conduct and agree to abide by it

[brokenpip3]

Can you please add a line in the changelog as well?

Also let me take advantage of this contribution (thanks!) to kindly ask you if you are willing to accept patches for the bash-bats-assert and bash-bats-support archlinux packages 'cause are still pointing to the old upstream (the ztombol one) instead of the bats-org 🙏

I tried to email you in the past about this, if you are willing to accept a patch for both the packages I can send it to you right away in your inbox :)
thanks and sorry for bothering about something not strict related to this PR

[felixonmars]

Updated :)

Sorry for overlooking that email - I have found it! I am willing to accept patches. Thanks!

[brokenpip3]

Thanks! I just sent the patches

[brokenpip3]

@martin-schulze-vireso I'm taking the responsibility to merge this PR, hope you don't mind