Version 0.1.5-2 of ocaml-http is marked for autoremoval from testing on Sun 07 Jun 2020. It depends (transitively) on gtksourceview2, affected by #911166. You should try to prevent the removal by fixing these RC bugs.
The current maintainer is looking for someone who can take over
maintenance of this package. If you are interested in this
package, please consider taking it over. Alternatively you may
want to be co-maintainer in order to help the actual
maintainer. Please see bug number #717787 for more information.