build(deps): bump net-imap from 0.5.6 to 0.5.8

Bumps [net-imap](https://github.com/ruby/net-imap) from 0.5.6 to 0.5.8.
- [Release notes](https://github.com/ruby/net-imap/releases)
- [Commits](ruby/net-imap@v0.5.6...v0.5.8)

---
updated-dependencies:
- dependency-name: net-imap
  dependency-version: 0.5.8
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -330,7 +330,7 @@ GEM
     multipart-post (2.4.1)
     net-http-persistent (4.0.4)
       connection_pool (~> 2.2)
-    net-imap (0.5.6)
+    net-imap (0.5.8)
       date
       net-protocol
     net-pop (0.1.2)