Update dependency sinatra to v2

Author: mend-for-github-com[bot]

samples/server/petstore/sinatra/Gemfile.lock

@@ -1,19 +1,31 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    rack (1.6.4)
-    rack-protection (1.5.3)
-      rack
-    sinatra (1.4.6)
-      rack (~> 1.4)
-      rack-protection (~> 1.4)
-      tilt (>= 1.3, < 3)
+    base64 (0.2.0)
+    mustermann (3.0.0)
+      ruby2_keywords (~> 0.0.1)
+    rack (3.1.7)
+    rack-protection (4.0.0)
+      base64 (>= 0.1.0)
+      rack (>= 3.0.0, < 4)
+    rack-session (2.0.0)
+      rack (>= 3.0.0)
+    ruby2_keywords (0.0.5)
+    sinatra (4.0.0)
+      mustermann (~> 3.0)
+      rack (>= 3.0.0, < 4)
+      rack-protection (= 4.0.0)
+      rack-session (>= 2.0.0, < 3)
+      tilt (~> 2.0)
     sinatra-cross_origin (0.3.2)
-    tilt (2.0.1)
+    tilt (2.4.0)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
   sinatra
   sinatra-cross_origin
+
+BUNDLED WITH
+   2.5.16