travis builds on "Focal" can't install valgrind and fails

[bagder]

The CI builds on travis that runs on Ubuntu "focal" can't install valgrind and fails.

According to a comment in our .travis.yml we use flocal for libssh builds because Avoid bionic, its pre-release libssh version triggers deprecation warnings.*

The following information may help to resolve the situation:
The following packages have unmet dependencies:
 valgrind : Depends: libc6-dbg but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
apt-get.diagnostics
apt-get install failed

The command "sudo -E apt-get -yq --no-install-suggests --no-install-recommends $(travis_apt_get_options) install cmake valgrind libev-dev libc-ares-dev g++-8 stunnel4 libidn2-dev gnutls-bin libssh-dev ninja-build" failed and exited with 100 during .

Your build has been stopped.