tests/test_memory.py: avoid spurious failures on non-linux.

Non-Linux machines have unreliable RSS values on Github.

scripts/gh_release.py: fixed to match lower-case sdist and wheel names.

setup.py: incremented default mupdf version to 1.24.11.

Update changelog, version numbers and dates for release of 1.24.13.

changes.txt: fixed incorrect list of supported Python versions - is 3…

….9-3.13.

Update version numbers and dates for release of 1.24.11.

changes.txt: updated for release of 1.24.10.

Also corrected MuPDF versions in some old changelog entries.

Update changelog, version numbers and release dates for release 1.24.9.

Also incremented MuPDF version to current latest release, 1.24.8.

In setup.py, include 'd' flavour by default; helps with testing.

setup.py: fix generation of mupdf header tree.

We cannot use `git ls-files` when building using the hard-coded MuPDF default
release because it is not a git checkout.

Update changelog, version numbers and release dates for release 1.24.7.