Bump execjs from 2.7.0 to 2.9.1

Bumps [execjs](https://github.com/rails/execjs) from 2.7.0 to 2.9.1.
- [Release notes](https://github.com/rails/execjs/releases)
- [Commits](rails/execjs@v2.7.0...v2.9.1)

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

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

Gemfile

@@ -2,7 +2,7 @@ source "https://rubygems.org"
 ruby '>= 2.6.4'
 
 gem "jekyll", "~> 4.0"
-gem "execjs", "2.7.0" # https://github.com/rails/execjs/issues/99
+gem "execjs", "2.9.1" # https://github.com/rails/execjs/issues/99
 gem "autoprefixer-rails"
 gem 'eventmachine', '1.2.7', git: 'https://github.com/eventmachine/eventmachine.git', tag: 'v1.2.7'
 

Gemfile.lock

@@ -42,7 +42,7 @@ GEM
       http_parser.rb (~> 0)
     ethon (0.15.0)
       ffi (>= 1.15.0)
-    execjs (2.7.0)
+    execjs (2.9.1)
     extras (0.3.0)
       forwardable-extended (~> 2.5)
     fastimage (2.2.6)
@@ -150,7 +150,7 @@ PLATFORMS
 DEPENDENCIES
   autoprefixer-rails
   eventmachine (= 1.2.7)!
-  execjs (= 2.7.0)
+  execjs (= 2.9.1)
   html-proofer (~> 3.18)
   jekyll (~> 4.0)
   jekyll-assets!