Bump sinatra from 2.0.8.1 to 2.2.3

Bumps [sinatra](https://github.com/sinatra/sinatra) from 2.0.8.1 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@v2.0.8.1...v2.2.3)

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

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

Author: dependabot[bot]

Gemfile.lock

@@ -280,7 +280,7 @@ GEM
     msgpack (1.3.3)
     multi_json (1.14.1)
     multipart-post (2.1.1)
-    mustermann (1.1.1)
+    mustermann (2.0.2)
       ruby2_keywords (~> 0.0.1)
     nakayoshi_fork (0.0.4)
     net-http-persistent (2.9.4)
@@ -314,7 +314,7 @@ GEM
       rack (>= 1.0, < 3)
     rack-contrib (2.2.0)
       rack (~> 2.0)
-    rack-protection (2.0.8.1)
+    rack-protection (2.2.3)
       rack
     rack-ssl (1.4.1)
       rack
@@ -358,7 +358,7 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.9.0)
     rspec-support (3.9.2)
-    ruby2_keywords (0.0.2)
+    ruby2_keywords (0.0.5)
     ruby_dep (1.5.0)
     safe_yaml (1.0.5)
     sentry-raven (2.11.3)
@@ -379,23 +379,22 @@ GEM
       docile (~> 1.1)
       simplecov-html (~> 0.11)
     simplecov-html (0.12.2)
-    sinatra (2.0.8.1)
-      mustermann (~> 1.0)
-      rack (~> 2.0)
-      rack-protection (= 2.0.8.1)
+    sinatra (2.2.3)
+      mustermann (~> 2.0)
+      rack (~> 2.2)
+      rack-protection (= 2.2.3)
       tilt (~> 2.0)
-    sinatra-contrib (2.0.8.1)
-      backports (>= 2.8.2)
+    sinatra-contrib (2.2.3)
       multi_json
-      mustermann (~> 1.0)
-      rack-protection (= 2.0.8.1)
-      sinatra (= 2.0.8.1)
+      mustermann (~> 2.0)
+      rack-protection (= 2.2.3)
+      sinatra (= 2.2.3)
       tilt (~> 2.0)
     stackdriver-core (1.4.0)
       google-cloud-core (~> 1.2)
     stackprof (0.2.15)
     thread_safe (0.3.6)
-    tilt (2.0.10)
+    tilt (2.0.11)
     timecop (0.9.1)
     tool (0.2.3)
     travis-rollout (0.0.2)