xpra:
* linkpac'ing packages to be built with Python3.11 for Leap 15.5 & Leap 15.6.
* 15.5 needs packages from devel:tools:compiler/15.5 to have the required devel packages to build.
* Adding this repo to SLED15SP6 also works

xpra-html5:
* doesn't _require_ Python3.11 to build, so leaving python3-* "Requires" in place.