Update mail to version 2.9.1

Author: depfu[bot]

Gemfile.lock

@@ -226,7 +226,7 @@ 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
@@ -245,12 +245,12 @@ GEM
       uri (>= 0.11.1)
     net-http-persistent (4.0.5)
       connection_pool (~> 2.2)
-    net-imap (0.6.4.1)
+    net-imap (0.6.6)
       date
       net-protocol
     net-pop (0.1.2)
       net-protocol
-    net-protocol (0.2.2)
+    net-protocol (0.3.0)
       timeout
     net-smtp (0.5.1)
       net-protocol