Bump sinatra-contrib from 2.0.5 to 2.0.8.1

Bumps [sinatra-contrib](https://github.com/sinatra/sinatra) from 2.0.5 to 2.0.8.1.
- [Release notes](https://github.com/sinatra/sinatra/releases)
- [Changelog](https://github.com/sinatra/sinatra/blob/master/CHANGELOG.md)
- [Commits](sinatra/sinatra@v2.0.5...v2.0.8.1)

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

Author: dependabot[bot]

Gemfile.lock

@@ -91,7 +91,7 @@ GEM
     azure_mgmt_traffic_manager (0.9.0)
       ms_rest_azure (~> 0.7.0)
     backport (1.1.2)
-    backports (3.11.4)
+    backports (3.18.1)
     beefcake (1.0.0)
     benchmark (0.1.0)
     bit-struct (0.16)
@@ -287,7 +287,8 @@ GEM
     multipart-parser (0.1.1)
     multipart-post (2.1.1)
     mustache (1.1.1)
-    mustermann (1.0.3)
+    mustermann (1.1.1)
+      ruby2_keywords (~> 0.0.1)
     mysql2 (0.5.2)
     net-ssh (5.0.2)
     netaddr (2.0.4)
@@ -317,7 +318,7 @@ GEM
       pry (~> 0.10)
     public_suffix (3.1.0)
     rack (2.2.3)
-    rack-protection (2.0.5)
+    rack-protection (2.0.8.1)
       rack
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -398,6 +399,7 @@ GEM
       rake (>= 0.8.1)
     ruby-mysql (2.9.14)
     ruby-progressbar (1.10.1)
+    ruby2_keywords (0.0.2)
     ruby_dep (1.5.0)
     ruby_parser (3.8.3)
       sexp_processor (~> 4.1)
@@ -416,18 +418,18 @@ GEM
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.2)
-    sinatra (2.0.5)
+    sinatra (2.0.8.1)
       mustermann (~> 1.0)
       rack (~> 2.0)
-      rack-protection (= 2.0.5)
+      rack-protection (= 2.0.8.1)
       tilt (~> 2.0)
-    sinatra-contrib (2.0.5)
+    sinatra-contrib (2.0.8.1)
       backports (>= 2.8.2)
       multi_json
       mustermann (~> 1.0)
-      rack-protection (= 2.0.5)
-      sinatra (= 2.0.5)
-      tilt (>= 1.3, < 3)
+      rack-protection (= 2.0.8.1)
+      sinatra (= 2.0.8.1)
+      tilt (~> 2.0)
     solargraph (0.39.8)
       backport (~> 1.1)
       benchmark
@@ -558,7 +560,7 @@ DEPENDENCIES
   rubyzip (>= 1.3.0)
   scientist (~> 1.1.0)
   sequel (~> 5.0)
-  sinatra (~> 2.0)
+  sinatra (= 2.0.8.1)
   sinatra-contrib
   solargraph
   spork!