Bump sinatra from 2.0.5 to 2.2.3

Bumps [sinatra](https://github.com/sinatra/sinatra) from 2.0.5 to 2.2.3.
- [Release notes](https://github.com/sinatra/sinatra/releases)
- [Changelog](https://github.com/sinatra/sinatra/blob/master/CHANGELOG.md)
- [Commits](https://github.com/sinatra/sinatra/compare/v2.0.5...v2.2.3)

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

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

Gemfile.lock

@@ -31,21 +31,23 @@ GEM
     gherkin (5.1.0)
     multi_json (1.15.0)
     multi_test (0.1.2)
-    mustermann (1.0.3)
+    mustermann (2.0.2)
-    rack (2.0.7)
+      ruby2_keywords (~> 0.0.1)
-    rack-protection (2.0.5)
+    rack (2.2.4)
+    rack-protection (2.2.3)
       rack
     rspec-expectations (3.11.0)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.11.0)
     rspec-support (3.11.0)
-    sinatra (2.0.5)
+    ruby2_keywords (0.0.5)
-      mustermann (~> 1.0)
+    sinatra (2.2.3)
-      rack (~> 2.0)
+      mustermann (~> 2.0)
-      rack-protection (= 2.0.5)
+      rack (~> 2.2)
+      rack-protection (= 2.2.3)
       tilt (~> 2.0)
     thor (1.2.1)
-    tilt (2.0.9)
+    tilt (2.0.11)
 
 PLATFORMS
   java