Bump sinatra from 2.1.0 to 2.2.3

Bumps [sinatra](https://github.com/sinatra/sinatra) from 2.1.0 to 2.2.3.
- [Release notes](https://github.com/sinatra/sinatra/releases)
- [Changelog](https://github.com/sinatra/sinatra/blob/master/CHANGELOG.md)
- [Commits](sinatra/sinatra@v2.1.0...v2.2.3)

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

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

Gemfile.lock

@@ -17,7 +17,7 @@ GEM
       kramdown (~> 2.0)
     mini_portile2 (2.4.0)
     mustache (1.1.1)
-    mustermann (1.1.1)
+    mustermann (2.0.2)
       ruby2_keywords (~> 0.0.1)
     nokogiri (1.10.10)
       mini_portile2 (~> 2.4.0)
@@ -26,7 +26,7 @@ GEM
       ast (~> 2.4.1)
     power_assert (1.2.0)
     rack (2.2.3.1)
-    rack-protection (2.1.0)
+    rack-protection (2.2.3)
       rack
     rainbow (3.0.0)
     rake (12.3.3)
@@ -44,15 +44,15 @@ GEM
     rubocop-ast (1.3.0)
       parser (>= 2.7.1.5)
     ruby-progressbar (1.10.1)
-    ruby2_keywords (0.0.2)
-    sinatra (2.1.0)
-      mustermann (~> 1.0)
+    ruby2_keywords (0.0.5)
+    sinatra (2.2.3)
+      mustermann (~> 2.0)
       rack (~> 2.2)
-      rack-protection (= 2.1.0)
+      rack-protection (= 2.2.3)
       tilt (~> 2.0)
     test-unit (3.3.7)
       power_assert
-    tilt (2.0.10)
+    tilt (2.0.11)
     unicode-display_width (1.7.0)
 
 PLATFORMS