fix(base): Allow variables which starts with _ be unused

Author: MorevM

configurations/base/rules/possible-problems.js

@@ -216,7 +216,7 @@ module.exports = {
 			args: 'none',
 			ignoreRestSiblings: true,
 			argsIgnorePattern: '^_*$',
-			varsIgnorePattern: '^_*$',
+			varsIgnorePattern: '^_',
 		}],
 
 		// Disallow early use