ci: Temporarily disable --fatal-meson-warnings on Hurd CI

For the same reasons as in commit 71061fdcb33b8c26f5f8467c, but in this
case we can’t downgrade the version of Meson on the CI runner, so just
tell it to shut up instead.

Signed-off-by: Philip Withnall <pwithnall@gnome.org>

Fixes: #3238

.gitlab-ci.yml

@@ -243,7 +243,12 @@ hurd-i386:
     - hurd
   needs: []
   script:
-    - meson setup ${MESON_COMMON_OPTIONS}
+    # FIXME: We can’t use ${MESON_COMMON_OPTIONS} here because the Hurd runner
+    # has Meson 1.3 installed. See the comment below about the same problem on
+    # FreeBSD.
+    - meson setup
+            --buildtype debug
+            --wrap-mode=nodownload
             --werror
             --default-library=both
             --prefix=$HOME/glib-installed