ci: Fix check-format

In commit bb6580212d we tried to stop
running check-format on debian. We did this by moving the check-format
details to its own map and then adding a "<<" merge key to only pull
it in on Fedora.

The Fedora map already has a "<<" merge key however for doing the actual
build.

It's not allowed for their to be two, and gitlab's ci just ignores
the second one.

This commit combines the merge keys into one.

.gitlab-ci.yml

@@ -19,8 +19,7 @@ fedora-x86_64:
   before_script:
     - dnf install -y gcc gtk3-devel git libpng-devel gettext-devel libxslt docbook-style-xsl cairo-devel systemd-devel systemd-udev kernel-headers libdrm-devel pango-devel make ShellCheck uncrustify patchutils meson binutils-gold xkeyboard-config-devel libevdev-devel
     - alternatives --set ld /usr/bin/ld.gold
-  <<: *check-format
-  <<: *meson-build
+  <<: [ *check-format, *meson-build ]
   only:
     - merge_requests