Add Linux Biolinum or Libertinus Sans to the classical humanist stack.

[matj1]

The stack of classical humanist fonts has Noto Sans for Linux, but Noto Sans it not classical, and Linux Biolinum and Libertinus Sans are available and present on many Linux systems.

I suggest that they would be in the stack for Linux Systems. The stack would be this:

font-family: Optima, 'Libertinus Sans', 'Linux Biolinum', Candara, 'Noto Sans', source-sans-pro, sans-serif;

I put them both in the stack because they are very similar, so, if Libertinus Sans is not installed, Linux Biolinum is used. But Libertinus Sans is first because it is a fork of Linux Biolinum, and has more refinements. Also, I put them before Candara because they are more similar to Optima, so, If someone has both Candara and Libertinus Sans, the used fond would be Libertinus Sans, not Candara. That makes the stack more consistent in a way that similar fonts are close together.