ci: Add workflow_dispatch to notify.yml

Isn't used right now. Just setting it up for testing purposes.

.github/workflows/notify.yml

@@ -4,6 +4,16 @@ on:
   release:
     types: [published]
 
+  workflow_dispatch:
+    inputs:
+      tag_name:
+        required: true
+        type: string
+        description: The release tag to generate a notification for
+
+env:
+  TAG: ${{ github.event.release.tag_name || github.event.inputs.tag_name }}
+
 jobs:
   notify:
     name: Discord Notification