Bump jwt from 2.1.0 to 2.2.1

Bumps [jwt](https://github.com/jwt/ruby-jwt) from 2.1.0 to 2.2.1.
- [Release notes](https://github.com/jwt/ruby-jwt/releases)
- [Changelog](https://github.com/jwt/ruby-jwt/blob/master/CHANGELOG.md)
- [Commits](https://github.com/jwt/ruby-jwt/compare/v2.1.0...v2.2.1)

Gemfile

@@ -34,7 +34,7 @@ gem 'stripe'
 # which is needed for Pin Payments (and possibly others).
 gem 'activemerchant', '~> 1.78'
 
-gem 'jwt', '~> 2.1'
+gem 'jwt', '~> 2.2'
 gem 'oauth2', '~> 1.4.1' # Used for Stripe Connect
 
 gem 'daemons'

Gemfile.lock

@@ -509,7 +509,7 @@ GEM
     json_spec (1.1.5)
       multi_json (~> 1.0)
       rspec (>= 2.0, < 4.0)
-    jwt (2.1.0)
+    jwt (2.2.1)
     kaminari (0.14.1)
       actionpack (>= 3.0.0)
       activesupport (>= 3.0.0)
@@ -831,7 +831,7 @@ DEPENDENCIES
   jquery-migrate-rails
   jquery-rails (= 3.0.4)
   json_spec (~> 1.1.4)
-  jwt (~> 2.1)
+  jwt (~> 2.2)
   knapsack
   letter_opener (>= 1.4.1)
   listen (= 3.0.8)