Discard local changes to git based vendor packages (#9813)

Fixes an update issue with the recent dependencies update.

composer.json

@@ -93,7 +93,8 @@
     "config": {
         "optimize-autoloader": true,
         "preferred-install": "dist",
-        "sort-packages": true
+        "sort-packages": true,
+        "discard-changes": true
     },
     "scripts": {
         "pre-update-cmd": "LibreNMS\\ComposerHelper::preUpdate",