Merge pull request #501 from citizensadvice/update-mail-gem

chore/Update mail gem

Author: KPobeeNorris

Gemfile.lock

@@ -199,7 +199,7 @@ GEM
     loofah (2.25.2)
       crass (~> 1.0.2)
       nokogiri (>= 1.12.0)
-    mail (2.9.0)
+    mail (2.9.1)
       logger
       mini_mime (>= 0.1.1)
       net-imap
@@ -213,7 +213,7 @@ GEM
       prism (~> 1.5)
     msgpack (1.8.4)
     multi_json (1.15.0)
-    net-imap (0.6.4.1)
+    net-imap (0.6.6)
       date
       net-protocol
     net-pop (0.1.2)