`latest-1` should match the highest version below the latest, not really latest minus 1

[mgol]

BrowserStack has just added macOS Tahoe with Safari 26. This trips up JTR logic for latest-1 as it expects to find version 25 which does not exist - it should use 18.4 instead.

Perhaps we should tweak the logic so that latest-1 means "the highest version with major lower than that of the latest one", not exactly "the major of the latest one minus 1".

[mgol]

The current logic is here:

jquery-test-runner/browserstack/api.js

Lines 200 to 206 in bbfa0f9

	// Get the latest version and subtract the number from the filter,
	// ignoring any patch versions, which may differ between major versions.
	const num = rlatest.exec( filterVersion );
	const version = parseInt( latest.browser_version ) - ( num ? num[ 1 ] : 0 );
	const match = group.findLast( ( browser ) => {
	return matchVersion( browser.browser_version, version.toString() );
	} );

[mgol]

An example jQuery CI failure because of this issue: https://github.com/jquery/jquery/actions/runs/16762647189/job/47461317392

Browser not found: Safari latest-1.

[timmywil]

This should be a simple change. It can get the previous based on previous one in the list, rather than assuming - 1 always exists.

[mgol]

This should be a simple change. It can get the previous based on previous one in the list

The only thing to take into account are duplicates. There may potentially be two browser versions with the same major, minor the same or different, we need to skip those when looking for -1.