Bump sinatra from 3.0.4 to 3.0.5 in /assets/loggregator-load-generator

Bumps [sinatra](https://github.com/sinatra/sinatra) from 3.0.4 to 3.0.5.
- [Release notes](https://github.com/sinatra/sinatra/releases)
- [Changelog](https://github.com/sinatra/sinatra/blob/master/CHANGELOG.md)
- [Commits](sinatra/sinatra@v3.0.4...v3.0.5)

---
updated-dependencies:
- dependency-name: sinatra
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

assets/loggregator-load-generator/Gemfile.lock

@@ -4,13 +4,13 @@ GEM
     mustermann (3.0.0)
       ruby2_keywords (~> 0.0.1)
     rack (2.2.4)
-    rack-protection (3.0.4)
+    rack-protection (3.0.5)
       rack
     ruby2_keywords (0.0.5)
-    sinatra (3.0.4)
+    sinatra (3.0.5)
       mustermann (~> 3.0)
       rack (~> 2.2, >= 2.2.4)
-      rack-protection (= 3.0.4)
+      rack-protection (= 3.0.5)
       tilt (~> 2.0)
     tilt (2.0.11)