Switch linter from semistandard to biome

Uses the recommended rules apart from complexity/useArrowFunction,
which would affect about 1700 lines of code with little benefit
right now. This is something that can be addressed over time.

test/unit/dilate.js

@@ -1,6 +1,4 @@
-'use strict';
-
-const assert = require('assert');
+const assert = require('node:assert');
 
 const sharp = require('../../');
 const fixtures = require('../fixtures');