remove ushort test

test/unit/avif.js

@@ -150,28 +150,4 @@ describe('AVIF', () => {
       () => sharp().avif({ bitdepth: 11 }),
       /Error: Expected 8, 10 or 12 for bitdepth but received 11 of type number/);
   });
-
-  it('should cast to ushort when bitdepth > 8', async () => {
-    const data = await sharp(inputJpg)
-      .resize(32)
-      .sharpen()
-      .avif({ effort: 0, bitdepth: 10 })
-      .toBuffer();
-    const { size, ...metadata } = await sharp(data)
-      .metadata();
-    assert.deepStrictEqual(metadata, {
-      channels: 3,
-      compression: 'av1',
-      depth: 'ushort',
-      format: 'heif',
-      hasAlpha: false,
-      hasProfile: false,
-      height: 26,
-      isProgressive: false,
-      pagePrimary: 0,
-      pages: 1,
-      space: 'srgb',
-      width: 32
-    });
-  });
 });