build(deps): bump mustermann from 3.0.2 to 3.0.3 in the bundler group

Bumps the bundler group with 1 update: [mustermann](https://github.com/sinatra/mustermann).


Updates `mustermann` from 3.0.2 to 3.0.3
- [Commits](sinatra/mustermann@v3.0.2...v3.0.3)

---
updated-dependencies:
- dependency-name: mustermann
  dependency-type: indirect
  update-type: version-update:semver-patch
  dependency-group: bundler
...

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

Gemfile.lock

@@ -59,7 +59,7 @@ GEM
     minitest (5.25.1)
     multi_xml (0.7.1)
       bigdecimal (~> 3.1)
-    mustermann (3.0.2)
+    mustermann (3.0.3)
       ruby2_keywords (~> 0.0.1)
     nenv (0.3.0)
     net-http (0.4.1)