Update stamina regeneration according to update 12.31

[omarcopires]

Pull Request Prelude

• I have followed proper The Forgotten Server code styling.
• I have read and understood the contribution guidelines before making this PR.
• I am aware that this PR may be closed if the above-mentioned criteria are not fulfilled.

Changes Proposed

This commit updates the stamina regeneration code to reflect the changes introduced in update 12.31, which lowered the regeneration rate of green stamina to 6 seconds per 1 second of stamina.
An option to use seconds instead of minutes was also added to make the code more readable.

Note: Needs testing before being added.

Issues addressed:
#3871