Update sass-rails to 6

(It is a wrapper for sassc: https://weblog.rubyonrails.org/2019/8/18/this-week-in-rails-rails-6-is-released-sass-rails-6-improved-mysql2-error-and-more/)

Author: emcoding

Gemfile

@@ -10,7 +10,7 @@ gem 'pg', '>= 0.18', '< 2.0'
 # Use Puma as the app server
 gem 'puma', '~> 3.11'
 # Use SCSS for stylesheets
-gem 'sass-rails', '~> 5'
+gem 'sass-rails', '~> 6'
 # Transpile app-like JavaScript. Read more: https://github.com/rails/webpacker
 gem 'webpacker', '~> 4.0'
 # Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks

Gemfile.lock

@@ -137,23 +137,22 @@ GEM
       rake (>= 0.8.7)
       thor (>= 0.20.3, < 2.0)
     rake (13.0.1)
-    rb-fsevent (0.10.3)
+    rb-fsevent (0.10.4)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     regexp_parser (1.7.0)
     ruby_dep (1.5.0)
     rubyzip (2.3.0)
-    sass (3.7.4)
-      sass-listen (~> 4.0.0)
-    sass-listen (4.0.0)
-      rb-fsevent (~> 0.9, >= 0.9.4)
-      rb-inotify (~> 0.9, >= 0.9.7)
-    sass-rails (5.1.0)
-      railties (>= 5.2.0)
-      sass (~> 3.1)
-      sprockets (>= 2.8, < 4.0)
-      sprockets-rails (>= 2.0, < 4.0)
-      tilt (>= 1.1, < 3)
+    sass-rails (6.0.0)
+      sassc-rails (~> 2.1, >= 2.1.1)
+    sassc (2.3.0)
+      ffi (~> 1.9)
+    sassc-rails (2.1.2)
+      railties (>= 4.0.0)
+      sassc (>= 2.0)
+      sprockets (> 3.0)
+      sprockets-rails
+      tilt
     selenium-webdriver (3.142.7)
       childprocess (>= 0.5, < 4.0)
       rubyzip (>= 1.2.2)
@@ -208,7 +207,7 @@ DEPENDENCIES
   pg (>= 0.18, < 2.0)
   puma (~> 3.11)
   rails (~> 6.0.0)
-  sass-rails (~> 5)
+  sass-rails (~> 6)
   selenium-webdriver
   spring
   spring-watcher-listen (~> 2.0.0)
@@ -222,4 +221,4 @@ RUBY VERSION
    ruby 2.7.0p0
 
 BUNDLED WITH
-   2.0.2
+   2.1.2