Bump net-imap from 0.5.1 to 0.5.2 in /spec/tester_mongo

Bumps [net-imap](https://github.com/ruby/net-imap) from 0.5.1 to 0.5.2.
- [Release notes](https://github.com/ruby/net-imap/releases)
- [Commits](ruby/net-imap@v0.5.1...v0.5.2)

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

Signed-off-by: dependabot[bot] <[email protected]>

spec/tester_mongo/Gemfile.lock

@@ -140,7 +140,7 @@ GEM
       mongo (>= 2.18.0, < 3.0.0)
     msgpack (1.7.5)
     mutex_m (0.3.0)
-    net-imap (0.5.1)
+    net-imap (0.5.2)
       date
       net-protocol
     net-pop (0.1.2)
@@ -226,7 +226,7 @@ GEM
     sqlite3 (1.6.9-x86_64-linux)
     stringio (3.1.2)
     thor (1.3.2)
-    timeout (0.4.2)
+    timeout (0.4.3)
     tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)
     websocket-driver (0.7.6)