Bump net-imap from 0.3.4 to 0.5.1

Bumps [net-imap](https://github.com/ruby/net-imap) from 0.3.4 to 0.5.1.
- [Release notes](https://github.com/ruby/net-imap/releases)
- [Commits](ruby/net-imap@v0.3.4...v0.5.1)

---
updated-dependencies:
- dependency-name: net-imap
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Gemfile.lock

@@ -154,7 +154,7 @@ GEM
       activerecord (>= 5.a)
       database_cleaner-core (~> 2.0.0)
     database_cleaner-core (2.0.1)
-    date (3.3.3)
+    date (3.4.1)
     debug_inspector (1.1.0)
     devise (4.8.1)
       bcrypt (~> 3.0)
@@ -293,12 +293,12 @@ GEM
     multi_json (1.15.0)
     multi_xml (0.6.0)
     nenv (0.3.0)
-    net-imap (0.3.4)
+    net-imap (0.5.1)
       date
       net-protocol
     net-pop (0.1.2)
       net-protocol
-    net-protocol (0.2.1)
+    net-protocol (0.2.2)
       timeout
     net-smtp (0.3.3)
       net-protocol
@@ -507,7 +507,7 @@ GEM
     thor (1.3.2)
     tilt (2.0.11)
     timecop (0.9.6)
-    timeout (0.3.1)
+    timeout (0.4.2)
     tinymce-rails (6.3.1)
       railties (>= 3.1.1)
     typhoeus (1.4.1)