fix: fix func names

Author: zdm

lib/loaders/json.js

@@ -1,4 +1,4 @@
-export default async function ( buffer, map, meta ) {
+export default async function jsonLoader ( buffer, map, meta ) {
     const callback = this.async(),
         options = this.getOptions();
 

lib/loaders/po.js

@@ -1,4 +1,4 @@
-export default async function ( buffer, map, meta ) {
+export default async function poLoader ( buffer, map, meta ) {
     const callback = this.async(),
         options = this.getOptions();
 

lib/loaders/yaml.js

@@ -1,4 +1,4 @@
-export default async function ( buffer, map, meta ) {
+export default async function yamlLoader ( buffer, map, meta ) {
     const callback = this.async(),
         options = this.getOptions();