Update the gitlab-ci to Fedora 32

Fedora 30 is end of life, let's use the version 32 instead.

Unfortunately, we have to disable taskswitch2 in the gitlab-ci now.
It does not seem to work anymore with the latest version of gcc and/or
QEMU. We still check it in the travis-ci, though, so until somebody has
some spare time to debug this issue, it should be ok to disable it here.

Message-Id: <20200514192626.9950-8-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>