TypeScript: Ensure 'FormatEnum' keys match reality #4475

Renames format.jp2k as format.jp2 for consistency

test/unit/jp2.js

@@ -11,7 +11,7 @@ const sharp = require('../../');
 const fixtures = require('../fixtures');
 
 describe('JP2 output', () => {
-  if (!sharp.format.jp2k.input.buffer) {
+  if (!sharp.format.jp2.input.buffer) {
     it('JP2 output should fail due to missing OpenJPEG', () =>
       assert.rejects(async () =>
         sharp(fixtures.inputJpg)