Bump sinatra from 2.0.0 to 2.0.2 in /example_app

Bumps [sinatra](https://github.com/sinatra/sinatra) from 2.0.0 to 2.0.2.
- [Release notes](https://github.com/sinatra/sinatra/releases)
- [Changelog](https://github.com/sinatra/sinatra/blob/master/CHANGELOG.md)
- [Commits](sinatra/sinatra@v2.0.0...v2.0.2)

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

Author: dependabot[bot]

example_app/Gemfile.lock

@@ -30,7 +30,8 @@ GEM
     mocha (1.3.0)
       metaclass (~> 0.0.1)
     multipart-post (2.0.0)
-    mustermann (1.0.1)
+    mustermann (1.1.1)
+      ruby2_keywords (~> 0.0.1)
     nokogiri (1.11.3)
       mini_portile2 (~> 2.5.0)
       racc (~> 1.4)
@@ -44,7 +45,7 @@ GEM
     rack (2.2.3)
     rack-flash3 (1.0.5)
       rack
-    rack-protection (2.0.0)
+    rack-protection (2.0.2)
       rack
     rack-test (0.7.0)
       rack (>= 1.0, < 3)
@@ -54,16 +55,17 @@ GEM
       ffi (>= 0.5.0, < 2)
     rerun (0.11.0)
       listen (~> 3.0)
+    ruby2_keywords (0.0.4)
     ruby_dep (1.5.0)
     sawyer (0.8.1)
       addressable (>= 2.3.5, < 2.6)
       faraday (~> 0.8, < 1.0)
-    sinatra (2.0.0)
+    sinatra (2.0.2)
       mustermann (~> 1.0)
       rack (~> 2.0)
-      rack-protection (= 2.0.0)
+      rack-protection (= 2.0.2)
       tilt (~> 2.0)
-    tilt (2.0.8)
+    tilt (2.0.10)
     xpath (2.1.0)
       nokogiri (~> 1.3)