Bump sinatra from 2.0.7 to 2.0.8.1

Bumps [sinatra](https://github.com/sinatra/sinatra) from 2.0.7 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@v2.0.7...v2.0.8.1)

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

Gemfile.lock

@@ -31,15 +31,16 @@ GEM
     jaro_winkler (1.5.4)
     json (2.2.0)
     msgpack (1.3.1)
-    mustermann (1.0.3)
+    mustermann (1.1.1)
+      ruby2_keywords (~> 0.0.1)
     nio4r (2.5.2)
     parallel (1.19.1)
     parser (2.6.5.0)
       ast (~> 2.4.0)
     puma (4.3.1)
       nio4r (~> 2.0)
     rack (2.0.8)
-    rack-protection (2.0.7)
+    rack-protection (2.0.8.1)
       rack
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -69,6 +70,7 @@ GEM
     rubocop-rspec (1.37.1)
       rubocop (>= 0.68.1)
     ruby-progressbar (1.10.1)
+    ruby2_keywords (0.0.1)
     serverengine (2.2.0)
       sigdump (~> 0.2.2)
     shotgun (0.9.2)
@@ -79,10 +81,10 @@ GEM
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.2)
-    sinatra (2.0.7)
+    sinatra (2.0.8.1)
       mustermann (~> 1.0)
       rack (~> 2.0)
-      rack-protection (= 2.0.7)
+      rack-protection (= 2.0.8.1)
       tilt (~> 2.0)
     strptime (0.2.3)
     temple (0.8.1)