Update phpseclib Vulerabilities and dependencies and set PHP 8.3 as minimum required version

[MajorOli]

Description

• Update addresses phpseclib Vulnerabilities and various dependencies
• Set PHP 8.3 to required minimum version
• Fix an issue at unit tests. There was possible to test features there required an active UnitTestUser and ignored the config in .env.testing
• Update Github Actions

Merge Request Checklists

• Code follows project coding guidelines.
• Documentation reflects the changes made.
• I have already covered the unit testing.