Bump omnibus from ae855f3 to 9c0643a in /omnibus (#6543)

Bumps [omnibus](https://github.com/chef/omnibus) from `ae855f3` to `9c0643a`.
- [Release notes](https://github.com/chef/omnibus/releases)
- [Commits](ae855f3060...9c0643a3a4)

---
updated-dependencies:
- dependency-name: omnibus
  dependency-type: direct:production
...

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

omnibus/Gemfile.lock

@@ -8,10 +8,10 @@ GIT
 
 GIT
   remote: https://github.com/chef/omnibus.git
-  revision: ae855f306015f1779684f490932a633055ececa6
+  revision: 9c0643a3a44f3e7119789c2093bfc8edd78c74ff
   branch: main
   specs:
-    omnibus (9.0.19)
+    omnibus (9.0.21)
       aws-sdk-s3 (~> 1.116.0)
       chef-cleanroom (~> 1.0)
       chef-utils (>= 15.4)
@@ -34,14 +34,14 @@ GEM
     artifactory (3.0.15)
     awesome_print (1.9.2)
     aws-eventstream (1.2.0)
-    aws-partitions (1.764.0)
-    aws-sdk-core (3.172.0)
+    aws-partitions (1.781.0)
+    aws-sdk-core (3.175.0)
       aws-eventstream (~> 1, >= 1.0.2)
       aws-partitions (~> 1, >= 1.651.0)
       aws-sigv4 (~> 1.5)
       jmespath (~> 1, >= 1.6.1)
-    aws-sdk-kms (1.64.0)
-      aws-sdk-core (~> 3, >= 3.165.0)
+    aws-sdk-kms (1.67.0)
+      aws-sdk-core (~> 3, >= 3.174.0)
       aws-sigv4 (~> 1.1)
     aws-sdk-s3 (1.116.0)
       aws-sdk-core (~> 3, >= 3.127.0)
@@ -248,7 +248,7 @@ GEM
       tomlrb (>= 1.2, < 3.0)
       tty-box (~> 0.6)
       tty-prompt (~> 0.20)
-    license_scout (1.3.5)
+    license_scout (1.3.6)
       ffi-yajl (~> 2.2)
       mixlib-shellout (>= 2.2, < 4.0)
       toml-rb (>= 1, < 3)
@@ -384,7 +384,7 @@ GEM
     toml-rb (2.2.0)
       citrus (~> 3.0, > 3.0)
     tomlrb (1.3.0)
-    train-core (3.10.7)
+    train-core (3.10.8)
       addressable (~> 2.5)
       ffi (!= 1.13.0)
       json (>= 1.8, < 3.0)