add gems back to custom gemfile

Author: fern-support

Gemfile.custom

@@ -12,3 +12,8 @@
 # end
 
 # Add your custom gem dependencies here
+
+group :test, :development do
+  gem 'mutex_m'
+  gem 'base64'
+end

Gemfile.lock

@@ -28,6 +28,7 @@ GEM
       faraday-net_http_persistent (~> 2.0)
       faraday-retry (~> 2.0)
     ast (2.4.3)
+    base64 (0.3.0)
     bigdecimal (3.3.1)
     certifi (2018.01.18)
     coderay (1.1.3)
@@ -67,6 +68,7 @@ GEM
     minitest-rg (5.3.0)
       minitest (~> 5.0)
     multipart-post (2.4.1)
+    mutex_m (0.3.0)
     net-http (0.8.0)
       uri (>= 0.11.1)
     net-http-persistent (4.0.6)
@@ -141,9 +143,11 @@ PLATFORMS
   x86_64-linux-musl
 
 DEPENDENCIES
+  base64
   minitest (~> 5.20, ~> 5.16)
   minitest-proveit (~> 1.0)
   minitest-rg
+  mutex_m
   pry
   rake (~> 13.0)
   rubocop (~> 1.21)