Bump net-imap from 0.5.1 to 0.5.6

Bumps [net-imap](https://github.com/ruby/net-imap) from 0.5.1 to 0.5.6.
- [Release notes](https://github.com/ruby/net-imap/releases)
- [Commits](ruby/net-imap@v0.5.1...v0.5.6)

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

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

Author: dependabot[bot]

Gemfile.lock

@@ -131,7 +131,7 @@ GEM
     coffee-script-source (1.12.2)
     concurrent-ruby (1.3.4)
     crass (1.0.6)
-    date (3.4.0)
+    date (3.4.1)
     debug_inspector (1.2.0)
     declarative (0.0.20)
     diff-lcs (1.5.1)
@@ -284,7 +284,7 @@ GEM
     multipart-post (2.4.1)
     net-http (0.4.1)
       uri
-    net-imap (0.5.1)
+    net-imap (0.5.6)
       date
       net-protocol
     net-pop (0.1.2)
@@ -474,7 +474,7 @@ GEM
     temple (0.10.3)
     thor (1.3.2)
     tilt (2.4.0)
-    timeout (0.4.2)
+    timeout (0.4.3)
     trailblazer-option (0.1.2)
     tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)