Downgrade sentry to work again.

Gemfile

@@ -42,7 +42,7 @@ gem 'rails-timeago'
 gem 'concurrent-ruby'
 gem 'mnemosyne-ruby'
 gem 'newrelic_rpm'
-gem 'sentry-raven'
+gem 'sentry-raven', '< 3'
 
 group :development, :staging do
   gem 'bootsnap', require: false

Gemfile.lock

@@ -130,7 +130,7 @@ GEM
     factory_bot_rails (5.1.1)
       factory_bot (~> 5.1.0)
       railties (>= 4.2.0)
-    faraday (1.0.0)
+    faraday (0.17.3)
       multipart-post (>= 1.2, < 3)
     faye-websocket (0.10.9)
       eventmachine (>= 0.12.0)
@@ -346,8 +346,8 @@ GEM
     selenium-webdriver (3.142.7)
       childprocess (>= 0.5, < 4.0)
       rubyzip (>= 1.2.2)
-    sentry-raven (3.0.0)
-      faraday (>= 1.0)
+    sentry-raven (2.13.0)
+      faraday (>= 0.7.6, < 1.0)
     shoulda-matchers (4.3.0)
       activesupport (>= 4.2.0)
     simplecov (0.18.5)
@@ -470,7 +470,7 @@ DEPENDENCIES
   rubyzip
   sass-rails
   selenium-webdriver
-  sentry-raven
+  sentry-raven (< 3)
   shoulda-matchers
   simplecov
   slim-rails