Upgrade omniauth-github to fix deprecation notice (#6022) [deploy]

Gemfile.lock

@@ -504,7 +504,7 @@ GEM
       nenv (~> 0.1)
       shellany (~> 0.0)
     oauth (0.5.4)
-    oauth2 (1.4.2)
+    oauth2 (1.4.3)
       faraday (>= 0.8, < 2.0)
       jwt (>= 1.0, < 3.0)
       multi_json (~> 1.3)
@@ -517,7 +517,7 @@ GEM
     omniauth (1.9.0)
       hashie (>= 3.4.6, < 3.7.0)
       rack (>= 1.6.2, < 3)
-    omniauth-github (1.3.0)
+    omniauth-github (1.4.0)
       omniauth (~> 1.5)
       omniauth-oauth2 (>= 1.4.0, < 2.0)
     omniauth-oauth (1.1.0)
@@ -563,7 +563,7 @@ GEM
       jwt (~> 2.1, >= 2.1.0)
       rest-client (~> 2.0, >= 2.0.2)
     pusher-signature (0.1.8)
-    rack (2.2.1)
+    rack (2.2.2)
     rack-host-redirect (1.3.0)
       rack
     rack-protection (2.0.5)