Add a deploy dispatch event (#214)

### Description

Allows someone with sufficient permissions to deploy the website by
issuing a dispatch event to this repository. This is needed to allow
other repository pushes to update the website.
 
### Issues Resolved

### Check List
- [X] Commits are signed per the DCO using `--signoff`

By submitting this pull request, I confirm that my contribution is made
under the terms of the BSD-3-Clause License.

---------

Signed-off-by: Madelyn Olson <madelyneolson@gmail.com>

Author: madolson

.github/workflows/zola-deploy.yml

@@ -3,7 +3,8 @@ name: Deploy website
 on:
   push:
     branches: ["main"]
-  
+  repository_dispatch:
+    types: [deploy]
   workflow_dispatch:
 
 permissions: