ghc-ticket links appear with %s prefix in 9.4.6 and 9.6.2 documentation

@juhp points out in this thread (00dc5106 (comment 519486)) that the ghc-ticket links are broken on the 9.4.6 documentation.

https://downloads.haskell.org/~ghc/9.4.6/docs/users_guide/9.4.6-notes.html

On my local build they look fine in both html and pdf.

[nix-shell:~/ghc-clean]$ sphinx-build --version
sphinx-build 5.3.0

in the docker image which builds the 9.4 documentation (registry.gitlab.haskell.org/ghc/ci-images/x86_64-linux-deb10:58d08589371e78829a3279c6f8b1241e155d7f70) seems quite ancient.

ghc@f53fe83dba94:~$ sphinx-build --version
sphinx-build 1.8.4