Ensure README changes don't affect whitespace

[AA-Turner]

str.splitlines() doesn't preserve trailing lines (unless using keepends=True), whereas str.split('\n') does. Use the latter form, and assert that modified files end with a blank line in tests.

A

[hugovk]

Suggested change

	lines = readme.read_text(encoding="utf-8").split("\n")
	lines = readme.read_text().split("\n")

I think we can skip this, we have a platform check:

release-tools/run_release.py

Lines 1375 to 1384 in a8981b1

	if sys.platform not in ("darwin", "linux"):
	print(
	"""\
	WARNING! This script has not been tested on a platform other than Linux and macOS.
	Although it should work correctly as long as you have all the dependencies,
	some things may not work as expected. As a release manager, you should try to
	fix these things in this script so it also supports your platform.
	"""
	)

And there's no RM using Windows now, or next. Perhaps the next one after Savannah will in 2028, but we can deal with it then (along with likely other Windows incompatibilities), and we might be using 3.15 as the minimum by then, with UTF-8 as default.

[hugovk]

Suggested change

	original_contents = original_readme_file.read_text(encoding="utf-8")
	original_contents = original_readme_file.read_text()

[hugovk]

Suggested change

	new_contents = readme_file.read_text(encoding="utf-8")
	new_contents = readme_file.read_text()