Bump net-imap from 0.6.4 to 0.6.4.1

Bumps [net-imap](https://github.com/ruby/net-imap) from 0.6.4 to 0.6.4.1.
- [Release notes](https://github.com/ruby/net-imap/releases)
- [Commits](https://github.com/ruby/net-imap/compare/v0.6.4...v0.6.4.1)

---
updated-dependencies:
- dependency-name: net-imap
  dependency-version: 0.6.4.1
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile.lock

@@ -159,7 +159,7 @@ GEM
       bigdecimal
       rexml
     crass (1.0.6)
-    date (3.5.0)
+    date (3.5.1)
     debug (1.11.0)
       irb (~> 1.10)
       reline (>= 0.3.8)
@@ -224,7 +224,7 @@ GEM
       ruby2_keywords (~> 0.0.1)
     net-http-persistent (4.0.6)
       connection_pool (~> 2.2, >= 2.2.4)
-    net-imap (0.6.4)
+    net-imap (0.6.4.1)
       date
       net-protocol
     net-pop (0.1.2)
@@ -380,7 +380,7 @@ GEM
     thruster (0.1.15-x86_64-darwin)
     thruster (0.1.15-x86_64-linux)
     tilt (2.6.1)
-    timeout (0.4.4)
+    timeout (0.6.1)
     tsort (0.2.0)
     tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)