chore(deps): bump sinatra from 1.4.4 to 1.4.8 in /tests/apps/ruby

Bumps [sinatra](https://github.com/sinatra/sinatra) from 1.4.4 to 1.4.8.
- [Release notes](https://github.com/sinatra/sinatra/releases)
- [Changelog](https://github.com/sinatra/sinatra/blob/master/CHANGELOG.md)
- [Commits](https://github.com/sinatra/sinatra/compare/v1.4.4...v1.4.8)

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

tests/apps/ruby/Gemfile

@@ -1,5 +1,5 @@
 source 'https://rubygems.org'
 ruby '2.1.5'
 
-gem 'sinatra', '~>1.4.4'
+gem 'sinatra', '~>1.4.8'
 gem 'thin'

tests/apps/ruby/Gemfile.lock

@@ -4,21 +4,21 @@ GEM
     daemons (1.3.1)
     eventmachine (1.2.7)
     rack (1.6.11)
-    rack-protection (1.5.2)
+    rack-protection (1.5.5)
       rack
-    sinatra (1.4.4)
-      rack (~> 1.4)
+    sinatra (1.4.8)
+      rack (~> 1.5)
       rack-protection (~> 1.4)
-      tilt (~> 1.3, >= 1.3.4)
+      tilt (>= 1.3, < 3)
     thin (1.7.2)
       daemons (~> 1.0, >= 1.0.9)
       eventmachine (~> 1.0, >= 1.0.4)
       rack (>= 1, < 3)
-    tilt (1.4.1)
+    tilt (2.0.10)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  sinatra (~> 1.4.4)
+  sinatra (~> 1.4.8)
   thin