Update plugins source.js add midjourney实现ai绘图的的插件

plugins/source.json

@@ -1,5 +1,9 @@
 {
   "repo": {
+    "midjourney": {
+      "url": "https://github.com/baojingyu/midjourney.git",
+      "desc": "利用midjourney实现ai绘图的的插件"
+    },
     "sdwebui": {
       "url": "https://github.com/lanvent/plugin_sdwebui.git",
       "desc": "利用stable-diffusion画图的插件"