DEV: add note explaining why omniauth-google-oauth2 is pinned

DEV: add note explaining why omniauth-google-oauth2 is pinned

diff --git a/Gemfile b/Gemfile
index 5673b00..10da7c5 100644
--- a/Gemfile
+++ b/Gemfile
@@ -87,7 +87,9 @@ gem 'omniauth-github'
 
 gem 'omniauth-oauth2', require: false
 
-gem 'omniauth-google-oauth2'
+# pinned until we test verified email change in the gem
+gem 'omniauth-google-oauth2', '0.6.0'
+
 gem 'oj'
 gem 'pg'
 gem 'mini_sql'

GitHub sha: 09638fcd