GH Actions/Securitycheck: update the security checker download

[jrfnl]

Proposed Changes

The security checker binary has had a few new releases, so let's take advantage of them.

Refs:

• https://github.com/fabpot/local-php-security-checker/releases
• https://github.com/fabpot/local-php-security-checker/blob/v2.0.0/CHANGELOG.md