Update test_notebooks.yml

.github/workflows/test_notebooks.yml

@@ -6,10 +6,6 @@ on:
   schedule:
   - cron:  '30 14 * * 1,3,5'
 
-  workflow_run:
-    branches:
-      - 'develop'
-
   # Allows you to run this workflow manually from the Actions tab
   workflow_dispatch:
 
@@ -25,6 +21,11 @@ jobs:
     steps:
       # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
       - uses: actions/checkout@v2
+        with:
+          # The branch, tag or SHA to checkout. When checking out the repository that
+          # triggered a workflow, this defaults to the reference or SHA for that event.
+          # Otherwise, defaults to `master`.
+          ref: 'develop'
       - uses: "actions/setup-python@v2"
         with:
           python-version: "3.6"