Bump omnibus from 9ffcd89 to a4bf7ea in /omnibus

Bumps [omnibus](https://github.com/chef/omnibus) from `9ffcd89` to `a4bf7ea`.
- [Release notes](https://github.com/chef/omnibus/releases)
- [Commits](chef/omnibus@9ffcd89...a4bf7ea)

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

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

omnibus/Gemfile.lock

@@ -7,7 +7,7 @@ GIT
 
 GIT
   remote: https://github.com/chef/omnibus.git
-  revision: 9ffcd89d078b3467be0480b138841ee82dd2d5d4
+  revision: a4bf7ea04b0d3689f9b8d172535f3976d07ecc1b
   specs:
     omnibus (8.1.15)
       aws-sdk-s3 (~> 1)
@@ -32,17 +32,17 @@ GEM
     ast (2.4.2)
     awesome_print (1.9.2)
     aws-eventstream (1.1.1)
-    aws-partitions (1.481.0)
-    aws-sdk-core (3.118.0)
+    aws-partitions (1.482.0)
+    aws-sdk-core (3.119.0)
       aws-eventstream (~> 1, >= 1.0.2)
       aws-partitions (~> 1, >= 1.239.0)
       aws-sigv4 (~> 1.1)
       jmespath (~> 1.0)
-    aws-sdk-kms (1.45.0)
-      aws-sdk-core (~> 3, >= 3.118.0)
+    aws-sdk-kms (1.46.0)
+      aws-sdk-core (~> 3, >= 3.119.0)
       aws-sigv4 (~> 1.1)
-    aws-sdk-s3 (1.97.0)
-      aws-sdk-core (~> 3, >= 3.118.0)
+    aws-sdk-s3 (1.98.0)
+      aws-sdk-core (~> 3, >= 3.119.0)
       aws-sdk-kms (~> 1)
       aws-sigv4 (~> 1.1)
     aws-sigv4 (1.2.4)