Bump sinatra from 1.3.6 to 2.2.3 in /hooks/ruby/dismiss-review-server

Bumps [sinatra](https://github.com/sinatra/sinatra) from 1.3.6 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@1.3.6...v2.2.3)

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

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

Author: dependabot[bot]

hooks/ruby/dismiss-review-server/Gemfile

@@ -2,4 +2,4 @@ source "https://rubygems.org"
 
 gem "json",        "~> 2.3"
 gem "rest-client"
-gem "sinatra",     "~> 1.3.5"
+gem "sinatra",     "~> 2.2.3"

hooks/ruby/dismiss-review-server/Gemfile.lock

@@ -9,19 +9,23 @@ GEM
     mime-types (3.1)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2016.0521)
+    mustermann (2.0.2)
+      ruby2_keywords (~> 0.0.1)
     netrc (0.11.0)
-    rack (1.6.13)
-    rack-protection (1.5.5)
+    rack (2.2.6.2)
+    rack-protection (2.2.3)
       rack
     rest-client (2.0.1)
       http-cookie (>= 1.0.2, < 2.0)
       mime-types (>= 1.16, < 4.0)
       netrc (~> 0.8)
-    sinatra (1.3.6)
-      rack (~> 1.4)
-      rack-protection (~> 1.3)
-      tilt (~> 1.3, >= 1.3.3)
-    tilt (1.4.1)
+    ruby2_keywords (0.0.5)
+    sinatra (2.2.3)
+      mustermann (~> 2.0)
+      rack (~> 2.2)
+      rack-protection (= 2.2.3)
+      tilt (~> 2.0)
+    tilt (2.1.0)
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.7.2)
@@ -32,7 +36,7 @@ PLATFORMS
 DEPENDENCIES
   json (~> 2.3)
   rest-client
-  sinatra (~> 1.3.5)
+  sinatra (~> 2.2.3)
 
 BUNDLED WITH
    1.14.4