Update previous_hackathons.yml

Author: DCGenomics

_data/previous_hackathons.yml

@@ -1,3 +1,13 @@
+- date: "June 25 - July 30, 2021"
+  loc: "Hack4Rare -- Childrens Tumor Foundation (Virtual)"
+  link: https://www.synapse.org/#!Synapse:syn25551331/wiki/609587
+  community access:  
+
+- date: "June 1-4, 2021"
+  loc: "MultiOmic Clinical Reporting! (Virtual) -- Carnegie Mellon University Libraries"
+  link: https://www.library.cmu.edu/about/publications/news/accepting-applications-hackathon-2021
+  community access:
+
 - date: "January 6-8, 2021"
   loc: "Bringing Genomic Data to the Clinic 2021 @CMU Libraries"
   link: https://forms.gle/gJysqAikunekP32B6