Bump sinatra from 2.1.0 to 2.2.0 in /ruby-admin-portal-example (#25)

Bumps [sinatra](https://github.com/sinatra/sinatra) from 2.1.0 to 2.2.0.
- [Release notes](https://github.com/sinatra/sinatra/releases)
- [Changelog](https://github.com/sinatra/sinatra/blob/master/CHANGELOG.md)
- [Commits](sinatra/sinatra@v2.1.0...v2.2.0)

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

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

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

Author: dependabot[bot]

ruby-admin-portal-example/Gemfile.lock

@@ -10,13 +10,13 @@ GEM
       coderay (~> 1.1)
       method_source (~> 1.0)
     rack (2.2.3)
-    rack-protection (2.1.0)
+    rack-protection (2.2.0)
       rack
     ruby2_keywords (0.0.5)
-    sinatra (2.1.0)
+    sinatra (2.2.0)
       mustermann (~> 1.0)
       rack (~> 2.2)
-      rack-protection (= 2.1.0)
+      rack-protection (= 2.2.0)
       tilt (~> 2.0)
     sorbet-runtime (0.5.9475)
     tilt (2.0.10)