pin sassc-rails to 2.1.0

See sass/sassc-ruby#189 (comment)

Author: apolopena

Gemfile

@@ -7,8 +7,8 @@ gem 'rails', '~> 6.1.3', '>= 6.1.3.1'
 gem 'pg', '~> 1.1'
 # Use Puma as the app server
 gem 'puma', '~> 5.0'
-# Use SCSS for stylesheets
-gem 'sassc-rails'
+# Use SCSS for stylesheets. Pin sasscc-rails to v2.1.0 to avoid 3-9 minute compile time. See https://github.com/sass/sassc-ruby/issues/189
+gem 'sassc-rails', '2.1.0'
 #gem 'sass-rails', '~> 5.0' # sass-rails is at end of lifetime
 # Use Uglifier as compressor for JavaScript assets
 gem 'uglifier', '>= 1.3.0'