ci: Temporarily disable --fatal-meson-warnings on msys2 CI

For the same reasons as in commit 71061fdcb3, but in this
case we can’t downgrade the version of Meson on the CI runner (see the
previous commit), so just tell it to shut up instead.

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

Helps: #3262

.gitlab-ci/test-msys2.sh

@@ -35,8 +35,13 @@ PATH="$(cygpath "$USERPROFILE")/.local/bin:$HOME/.local/bin:$PATH"
 DIR="$(pwd)"
 export PATH CFLAGS
 
+# FIXME: We can’t use ${MESON_COMMON_OPTIONS} here because this script installs
+# Meson 1.3. See the comment in .gitlab-ci.yml about the same problem on
+# FreeBSD.
 # shellcheck disable=SC2086
-meson setup ${MESON_COMMON_OPTIONS} \
+meson setup \
+    --buildtype=debug \
+    --wrap-mode=nodownload \
     --werror \
     -Ddocumentation=true \
     -Dintrospection=enabled \