Fix deploy workflow syntax and add dev branch support

.github/workflows/deploy.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - main
+      - dev
 
 jobs:
   push_to_target_repository:
@@ -17,12 +18,14 @@ jobs:
 
       - uses: webfactory/ssh-agent@v0.8.0
         with:
-            ssh-private-key: ${{ github.action.secrets.SSH_PRIVATE_KEY }}
+            ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
 
       - name: Push to dokku
         env:
-            HOST_KEY: ${{ github.action.secrets.HOST_KEY }}
+            HOST_KEY: ${{ secrets.HOST_KEY }}
         run: |
-            echo $HOST_KEY > ~/.ssh/known_hosts
+            mkdir -p ~/.ssh
+            echo "$HOST_KEY" > ~/.ssh/known_hosts
+            chmod 600 ~/.ssh/known_hosts
             git remote add dokku dokku@v2.discours.io:discoursio-api
             git push dokku HEAD:main -f