GH Actions/Securitycheck: update the security checker download

[jrfnl]

Proposed Changes

The security checker binary has had a new release. I've reviewed the diff, changes look fine.

Refs:

• https://github.com/fabpot/local-php-security-checker/releases/tag/v2.0.5
• https://github.com/fabpot/local-php-security-checker/compare/v2.0.4...v2.0.5