Fix #1159 ensure appname pr preview last character is always alphanumeric

Author: chrisjsimpson

.github/workflows/pr-demo-deploy.yml

@@ -43,7 +43,8 @@ jobs:
       - name: Set subdomain (ensure is lowercase for dokku)
         run: |
           set -x
-          echo SUBDOMAIN=`echo "${{ github.head_ref }}" | tr '[:upper:]' '[:lower:]' | cut -c -60` >> $GITHUB_ENV
+          # Enforce max 60 chars, always end with alnum char
+          echo SUBDOMAIN=`echo "${{ github.head_ref }}" | tr '[:upper:]' '[:lower:]' | cut -c -60 | rev | sed 's/[^[:alnum:]]//1' | rev` >> $GITHUB_ENV
           echo $GITHUB_ENV
       - name: Create dokku app for pr branch if dosent already exist using dokku apps:create
         env: