Add YouTube URL for Reproducibility talk

Author: kellychang4

_data/calendar.yaml

@@ -16,7 +16,7 @@
         title: 'Reproducibility in Cognitive Neuroscience: What is the Problem?'
         speakers:
         - Russell Poldrack
-        # youtube_url: 
+        youtube_url: https://youtu.be/Gto8Y8KRBLA
       - time: 12:00pm
         title: Lunch
         speakers: []