build(ci): run the mockbuild-all unit tests

t/mockbuild-all.t covers the manifest gate and the skip-run carry-over and
was not in the package test job. Its rpm fixtures skip where rpmbuild is
absent.

Signed-off-by: Vinícius Ferrão <2031761+viniciusferrao@users.noreply.github.com>

.github/workflows/genesis-openembedded.yml

@@ -57,5 +57,6 @@ jobs:
           prove -v t/build_utils.t
           prove -v t/build_timeout.t
           prove -v t/sbuild-all.t
+          prove -v t/mockbuild-all.t
           prove -v -It/lib t/genesis_openembedded_release.t
           sudo -E prove -v -It/lib t/genesis_openembedded_consumer.t