Update build.yml to take account of environment and only trigger of commits to main (which is implicitly when a PR is merged to main anyway)

Author: seanlandsman

.github/workflows/build.yml

@@ -1,10 +1,9 @@
 name: Build release
 
 on:
-  pull_request:
+  push:
     branches:
       - main
-    types: [closed]
 
 env:
   CI: true
@@ -19,8 +18,7 @@ jobs:
     permissions:
       contents: write
     runs-on: ubuntu-latest
-    environment: production # will be develop.
-    if: github.event.pull_request.merged
+    environment: production
     steps:
       - name: Authenticate with GitHub App
         uses: actions/create-github-app-token@v1
@@ -54,7 +52,7 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ steps.app-token.outputs.token }}
         with:
-          commitish: ${{ github.ref }}
+          commitish: ${{ github.sha }}
           tag_name: ${{ steps.version.outputs.VERSION }}
           release_name: ${{ steps.version.outputs.VERSION }}
           draft: false