Bump net-imap from 0.4.16 to 0.4.19

Bumps [net-imap](https://github.com/ruby/net-imap) from 0.4.16 to 0.4.19.
- [Release notes](https://github.com/ruby/net-imap/releases)
- [Commits](ruby/net-imap@v0.4.16...v0.4.19)

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

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

Author: dependabot[bot]

Gemfile.lock

@@ -129,7 +129,7 @@ GEM
     concurrent-ruby (1.3.4)
     connection_pool (2.4.1)
     crass (1.0.6)
-    date (3.3.4)
+    date (3.4.1)
     debug (1.10.0)
       irb (~> 1.10)
       reline (>= 0.3.8)
@@ -184,7 +184,7 @@ GEM
     multi_json (1.15.0)
     mustermann (3.0.3)
       ruby2_keywords (~> 0.0.1)
-    net-imap (0.4.16)
+    net-imap (0.4.19)
       date
       net-protocol
     net-pop (0.1.2)
@@ -338,7 +338,7 @@ GEM
     thruster (0.1.9-x86_64-darwin)
     thruster (0.1.9-x86_64-linux)
     tilt (2.4.0)
-    timeout (0.4.1)
+    timeout (0.4.3)
     turbo-rails (2.0.11)
       actionpack (>= 6.0.0)
       railties (>= 6.0.0)