Bump omnibus from 999a4e0 to e3573e7 in /omnibus

Bumps [omnibus](https://github.com/chef/omnibus) from `999a4e0` to `e3573e7`.
- [Release notes](https://github.com/chef/omnibus/releases)
- [Commits](chef/omnibus@999a4e0...e3573e7)

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

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

omnibus/Gemfile.lock

@@ -7,9 +7,9 @@ GIT
 
 GIT
   remote: https://github.com/chef/omnibus.git
-  revision: 999a4e0cb8b5aad5490f01c3ef25489883087cd6
+  revision: e3573e77f3de5944a2fcd998ba50c773c2212ab7
   specs:
-    omnibus (8.2.0)
+    omnibus (8.2.1)
       aws-sdk-s3 (~> 1)
       chef-cleanroom (~> 1.0)
       chef-utils (>= 15.4)