Bump scout_apm from 5.2.0 to 5.3.1

Bumps [scout_apm](https://github.com/scoutapp/scout_apm_ruby) from 5.2.0 to 5.3.1.
- [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/v5.2.0...v5.3.1)

---
updated-dependencies:
- dependency-name: scout_apm
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Gemfile.lock

@@ -417,7 +417,7 @@ GEM
       rack
     orm_adapter (0.5.0)
     parallel (1.22.1)
-    parser (3.1.2.0)
+    parser (3.1.2.1)
       ast (~> 2.4.1)
     percy-capybara (5.0.0)
       capybara (>= 3)
@@ -570,7 +570,7 @@ GEM
       sprockets (> 3.0)
       sprockets-rails
       tilt
-    scout_apm (5.2.0)
+    scout_apm (5.3.1)
       parser
     searchkick (4.6.3)
       activemodel (>= 5)