CI: Install the newly-built libcurl shim
For multi-arch co-installability after upgrading to a scout image that includes the libcurl shim, if we install all amd64 .debs, then we will also need to upgrade the corresponding version of Multi-Arch: same i386 .debs to a matching version.
Fixes: 95cf1fef "debian: Build libcurl compat shim ..."
Edited by Simon McVittie