fix(authelia): fix typo in theme selection

[stavros-k]

Description

Fixes #1393
Type of change

• Feature/App addition
• Bugfix
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactor of current code

How Has This Been Tested?

Notes:

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests to this description that prove my fix is effective or that my feature works
• I increased versions for any altered app according to semantic versioning

[truecharts-admin]

This PR is locked to prevent necro-posting on closed PRs. Please create a issue or contact staff on discord if you want to further discuss this