Update team.yaml

Change Georgy's github handle to @gmanuch, per his request

Author: emiliom

_ext/team.yaml

@@ -222,7 +222,7 @@ team:
     title: Assistant Professor
     affiliate: UW School of Oceanography
     image_url: https://www.ocean.washington.edu/files/dsc_0104-20191128052712_smsq.jpg
-    github_user: ONR-MURI
+    github_user: gmanuch
     email: gmanuch@uw.edu
     roles:
       - Projects