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] <[email protected]>

Gemfile.lock

@@ -108,7 +108,7 @@ GEM
     mini_portile2 (2.8.8)
     minitest (5.25.4)
     nanoid (2.0.0)
-    net-imap (0.5.1)
+    net-imap (0.5.6)
       date
       net-protocol
     net-pop (0.1.2)
@@ -194,7 +194,7 @@ GEM
       activesupport (>= 5.2)
       sprockets (>= 3.0.0)
     thor (1.2.1)
-    timeout (0.4.2)
+    timeout (0.4.3)
     tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)
     unicode-display_width (2.4.2)