Bump net-imap from 0.6.2 to 0.6.3 in /builder (#2958)

Bumps [net-imap](https://github.com/ruby/net-imap) from 0.6.2 to 0.6.3.
- [Release notes](https://github.com/ruby/net-imap/releases)
- [Commits](ruby/net-imap@v0.6.2...v0.6.3)

---
updated-dependencies:
- dependency-name: net-imap
  dependency-version: 0.6.3
  dependency-type: indirect
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

builder/Gemfile.lock

@@ -155,7 +155,7 @@ GEM
       prism (~> 1.5)
     msgpack (1.8.0)
     mutex_m (0.3.0)
-    net-imap (0.6.2)
+    net-imap (0.6.3)
       date
       net-protocol
     net-pop (0.1.2)