Update version to 3.1.5

Author: nhielost

buildspec.json

@@ -41,7 +41,7 @@
     },
     "name": "obs-midi-mg",
     "displayName": "obs-midi-mg",
-    "version": "3.1.4",
+    "version": "3.1.5",
     "author": "nhielost",
     "email": "nhielost@gmail.com",
     "website": "https://github.com/nhielost/obs-midi-mg"