Update Scout to latest version

Running into a "stack level too deep" error:
/GEM_ROOT/gems/scout_apm-2.6.10/lib/scout_apm/layer_children_set.rb:30

Updating Scout to see if that fixes it.

Refs: #2872

Gemfile

@@ -58,7 +58,7 @@ gem "sidekiq", "~> 6.2"
 
 gem "airbrake", "~> 11.0.3"
 gem "newrelic_rpm", "~> 7.1.0"
-gem "scout_apm", "~> 2.4"
+gem "scout_apm", "~> 4.1"
 
 gem "dalli", "~> 2.7"
 

Gemfile.lock

@@ -449,7 +449,7 @@ GEM
       sprockets (> 3.0)
       sprockets-rails
       tilt
-    scout_apm (2.6.10)
+    scout_apm (4.1.1)
       parser
     selenium-webdriver (3.142.7)
       childprocess (>= 0.5, < 4.0)
@@ -600,7 +600,7 @@ DEPENDENCIES
   rails_autoscale_agent
   rspec-rails (~> 5.0)
   sass-rails (~> 6.0)
-  scout_apm (~> 2.4)
+  scout_apm (~> 4.1)
   sidekiq (~> 6.2)
   simple_form (~> 5.0)
   spring (~> 2.0)