Bump scout_apm from 2.5.2 to 2.6.0 (#4040)

Bumps [scout_apm](https://github.com/scoutapp/scout_apm_ruby) from 2.5.2 to 2.6.0.
- [Release notes](https://github.com/scoutapp/scout_apm_ruby/releases)
- [Changelog](https://github.com/scoutapp/scout_apm_ruby/blob/master/CHANGELOG.markdown)
- [Commits](https://github.com/scoutapp/scout_apm_ruby/compare/v2.5.2...v2.6.0)

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

Gemfile

@@ -80,7 +80,7 @@ gem "rubyzip", "~> 1.2" # Rubyzip is a ruby library for reading and writing zip
 gem "s3_direct_upload", "~> 0.1" # Direct Upload to Amazon S3
 gem "sail", "~> 1.5" # Sail is a lightweight Rails engine that brings an admin panel for managing configuration settings on a live Rails app
 gem "sass-rails", "~> 5.1" # Sass adapter for the Rails asset pipeline
-gem "scout_apm", "~> 2.5" # Monitors Ruby apps and reports detailed metrics on performance to Scout
+gem "scout_apm", "~> 2.6" # Monitors Ruby apps and reports detailed metrics on performance to Scout
 gem "serviceworker-rails", "~> 0.6" # Integrates ServiceWorker into the Rails asset pipeline
 gem "sitemap_generator", "~> 6.0" # SitemapGenerator is a framework-agnostic XML Sitemap generator
 gem "skylight", "~> 4.1" # Skylight is a smart profiler for Rails, Sinatra, and other Ruby apps

Gemfile.lock

@@ -699,7 +699,8 @@ GEM
       addressable (>= 2.3.5)
       faraday (> 0.8, < 2.0)
     sax-machine (1.3.2)
-    scout_apm (2.5.2)
+    scout_apm (2.6.0)
+      parser
     sdoc (1.0.0)
       rdoc (>= 5.0)
     selectize-rails (0.12.6)
@@ -951,7 +952,7 @@ DEPENDENCIES
   s3_direct_upload (~> 0.1)
   sail (~> 1.5)
   sass-rails (~> 5.1)
-  scout_apm (~> 2.5)
+  scout_apm (~> 2.6)
   sdoc (~> 1.0)
   serviceworker-rails (~> 0.6)
   shoulda-matchers (= 4.1.2)