I believe that this is suggesting that the version on CRAN is not yet compatible with your version of R, but that the in-development version on GitHub might be.
When this happens, it can often be helpful to do a websearch for "GitHub [packagename]" - and if you find a GitHub website that sounds like the right package, you can install the in-development version.
Take a look at GitHub - bbuchfink/diamond: Accelerated BLAST compatible local sequence aligner. and see if it looks like the package that you want.
In this case (assuming that this is the right package), you can use
remotes::install_github("bbuchfink/diamond") to install the development version and give it a try.
There does not appear to be a 'diamond' package available on CRAN. CRAN Packages By Name - is it possible that you are looking for the 'diamonds' dataset? This is part of the ggplot2 package.