fix: eqeqeq rule deprecated option allow-null

[nirtamir2]

According to the eqeqeq rule docs - option allow-null is deprecated.

https://eslint.org/docs/rules/eqeqeq#allow-null

Deprecated: Instead of using this option use "always" and pass a "null" option property with value "ignore". This will tell ESLint to always enforce strict equality except when comparing with the null literal.

This PR fixes it to use the null option.

NOTICE: If you prefer, eqeqeq has also smart option instead of always but it behaves differently.

[antfu]

Let's go smart! Thanks!