A more compatible kludge for rpm-software-management#3278

The one from commit 8ce8afe doesn't
work on Fedora 39, but since dnf appears to merrily take a version
range on the cli...

tests/Dockerfile.fedora

@@ -46,7 +46,7 @@ RUN dnf -y install \
   tar unzip gzip bzip2 cpio xz p7zip \
   pkgconfig \
   /usr/bin/systemd-sysusers \
-  gdb-headless-14.2 \
+  "gdb-headless < 15" \
   dwz \
   fsverity-utils fsverity-utils-devel \
   pandoc \