ci: Downgrade libX11 to avoid a bug in teardown

Xlib would always report the error

  XIO:  fatal IO error 9 (Bad file descriptor) on X server ":102"

when mutter is tearing down. This behavior changed somewhere between
version 1.8.7 to 1.8.10 and is tracked at
https://gitlab.freedesktop.org/xorg/lib/libx11/-/merge_requests/264.

Until we have a fixed libX11, we downgrade it to a known-good version.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3918>

.gitlab-ci.yml

@@ -96,7 +96,7 @@ variables:
     - .skip-git-clone
   variables:
     FDO_DISTRIBUTION_VERSION: 40
-    BASE_TAG: '2024-08-03.0'
+    BASE_TAG: '2024-08-03.1'
     MUTTER_USER: 'meta-user'
     FDO_DISTRIBUTION_PACKAGES:
       asciidoc
@@ -133,6 +133,12 @@ variables:
       dnf builddep -y gi-docgen --setopt=install_weak_deps=False
       dnf builddep -y wayland --setopt=install_weak_deps=False
 
+      # FIXME: we downgrade xlib to 1.8.7 because somewhere on the way to
+      # version 1.8.10, a bug was introdcued
+      # https://gitlab.freedesktop.org/xorg/lib/libx11/-/merge_requests/264
+      # Remove when we have a fixed version!
+      dnf install -y libX11-common-1.8.7
+
       ./.gitlab-ci/install-meson-project.sh \
         https://gitlab.gnome.org/jadahl/catch.git \
         main