Backport GHSA-73rr-hh4g-fpgx fix to v4

[G-Rath]

Sorry in advance, but would you be open to backporting this fix, especially to the v4 line? I agree with the comments around the signal vs noise of ReDOS vulns, but v4 in particular is the most downloaded major (probably no in small part due to its use by tools like ts-node).

It looks to me like the patch should apply without any modifications thankfully:

jsdiff/src/patch/parse.js

Lines 20 to 26 in 94b63ff

	// Diff index
	let header = (/^(?:Index:|diff(?: -r \w+)+)\s+(.+?)\s*$/).exec(line);
	if (header) {
	index.index = header[1];
	}
	i++;

I'm happy to help out anyway I can, to reduce the work required by maintainers