Add ability to manually generate verifiable builds

Author: metaproph3t

.github/workflows/generate-verifiable-builds.yaml

@@ -1,5 +1,6 @@
 name: generate-verifiable-builds
 on:
+  workflow_dispatch:
   push:
     branches:
       - production
@@ -53,4 +54,4 @@ jobs:
         uses: EndBug/add-and-commit@v9.1.4
         with:
           default_author: github_actions
-          message: 'Update autocrat_migrator verifiable build'
+          message: 'Update autocrat_migrator verifiable build'