Should help catch errors like initializing a q-ptr with itself[1].

[1] https://invent.kde.org/frameworks/knewstuff/-/commit/d09ba1917cb7e035a9aac6c27c86fc4df5da3194

I was seeing `error: No such remote 'origin'` in the cmake output.
This commit avoids hardcoding `origin` as the upstream URL and instead
uses the `git rev-parse @{u}` to get the configured upstream.

As a follow-up we may want to check if this should be executed by default,
but for now this fixes a warning that I'm seeing with various projects.

Plain freedesktop.org 302-redirects to www.freedesktop.org.

Also, fixes a warning during CMake generation step in plasma-desktop.
See https://invent.kde.org/plasma/plasma-desktop/-/merge_requests/572

The proximate problem is that the Python Module generator cmake script
has started failing for people with Python 3.10, which a CMake backtrace
pointing into FindPythonModuleGeneration.cmake with an error of the form
"The max python version in PythonModuleGeneration must be updated."

At least one distro has addressed this by simply patching out modules
that happen to use this CMake module [1].

From what I can tell and the testing I've done, the cause is pretty
simple: The CMake script attempts to find the best Python 3 version by
starting from an impossible version and working backwards until it finds
a version that is installed.

As a sanity check, if the "impossible" version is actually present, it
aborts. But this appears to be just a sanity check, and not any sort of
guard against buggy version handling code later.

While the best fix is probably to start from a known *good* version and
move up until we stop finding better versions, there's problems here
(e.g. a user with 3.6 and 3.8 installed would fail to see 3.7 and so be
left with 3.6 as the "best" match), so I opted just to increase the max
version significantly, and improve the documentation as to what's
happening and whether it is safe to repeat the step again later.

[1]: https://bugs.gentoo.org/746866

wl_resource_for_each_safe is used in kwayland-server, and as the name
suggests is a for-each like function.

And the generated html looks more correct

If people ship their own clang-format file they might still have the copyright, because
they forked it. Instead search for the notice that the file is autogenerated.