feat(locales): add Lithuanian translation (#4761)

packages/netlify-cms-locales/src/index.js

@@ -8,6 +8,7 @@ export { default as fr } from './fr';
 export { default as gr } from './gr';
 export { default as hu } from './hu';
 export { default as it } from './it';
+export { default as lt } from './lt';
 export { default as ja } from './ja';
 export { default as nl } from './nl';
 export { default as nb_no } from './nb_no';