Dev: remove supportOldDangerousPassword before v1.0.0 release

[kenjis]

See https://github.com/codeigniter4/shield/blob/develop/UPGRADING.md#if-you-want-to-allow-login-with-existing-passwords

shield/src/Config/Auth.php

Lines 377 to 385 in 0bf28b2

	/**
	* If you need to support passwords saved in versions prior to Shield v1.0.0-beta.4.
	* set this to true.
	*
	* See https://github.com/codeigniter4/shield/security/advisories/GHSA-c5vj-f36q-p9vg
	*
	* @deprecated This is only for backward compatibility.
	*/
	public bool $supportOldDangerousPassword = false;

[omerimzali]

@kenjis I sent a PR for the issue.