Error when using sassc-rails

Hi and many thanks for your work to build a Ruby gem for tabler UI.

I've started with a fresh Rails (5.2.2.1) app which uses `sassc-rails` instead of `sass-rails`due to the deprecation warnings for sass.

When I start the (development) server with `rails s` I get the following error:

```
Traceback (most recent call last):
bin/rails: Bootsnap::LoadPathCache::FallbackScan
50: from bin/rails:3:in `'
49: from bin/rails:3:in `load'
48: from /Users///bin/spring:15:in `'
47: from /Users//.rbenv/versions/2.6.2/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
46: from /Users//.rbenv/versions/2.6.2/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
45: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/spring-2.0.2/lib/spring/binstub.rb:31:in `'
44: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/spring-2.0.2/lib/spring/binstub.rb:31:in `load'
43: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/spring-2.0.2/bin/spring:49:in `'
42: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/spring-2.0.2/lib/spring/client.rb:30:in `run'
41: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/spring-2.0.2/lib/spring/client/command.rb:7:in `call'
40: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/spring-2.0.2/lib/spring/client/rails.rb:28:in `call'
39: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/spring-2.0.2/lib/spring/client/rails.rb:28:in `load'
38: from /Users///bin/rails:9:in `'
37: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/activesupport-5.2.2.1/lib/active_support/dependencies.rb:291:in `require'
36: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/activesupport-5.2.2.1/lib/active_support/dependencies.rb:257:in `load_dependency'
35: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/activesupport-5.2.2.1/lib/active_support/dependencies.rb:291:in `block in require'
34: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:29:in `require'
33: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:20:in `require_with_bootsnap_lfi'
32: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/loaded_features_index.rb:83:in `register'
31: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `block in require_with_bootsnap_lfi'
30: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require'
29: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/railties-5.2.2.1/lib/rails/commands.rb:18:in `'
28: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/railties-5.2.2.1/lib/rails/command.rb:46:in `invoke'
27: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/railties-5.2.2.1/lib/rails/command/base.rb:65:in `perform'
26: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/thor-0.20.3/lib/thor.rb:387:in `dispatch'
25: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/thor-0.20.3/lib/thor/invocation.rb:126:in `invoke_command'
24: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/thor-0.20.3/lib/thor/command.rb:27:in `run'
23: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/railties-5.2.2.1/lib/rails/commands/server/server_command.rb:142:in `perform'
22: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/railties-5.2.2.1/lib/rails/commands/server/server_command.rb:142:in `tap'
21: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/railties-5.2.2.1/lib/rails/commands/server/server_command.rb:145:in `block in perform'
20: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/activesupport-5.2.2.1/lib/active_support/dependencies.rb:291:in `require'
19: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/activesupport-5.2.2.1/lib/active_support/dependencies.rb:257:in `load_dependency'
18: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/activesupport-5.2.2.1/lib/active_support/dependencies.rb:291:in `block in require'
17: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:29:in `require'
16: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:20:in `require_with_bootsnap_lfi'
15: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/loaded_features_index.rb:83:in `register'
14: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `block in require_with_bootsnap_lfi'
13: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require'
12: from /Users///config/application.rb:18:in `'
11: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bundler-2.0.1/lib/bundler.rb:114:in `require'
10: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bundler-2.0.1/lib/bundler/runtime.rb:65:in `require'
9: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bundler-2.0.1/lib/bundler/runtime.rb:65:in `each'
8: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bundler-2.0.1/lib/bundler/runtime.rb:76:in `block in require'
7: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bundler-2.0.1/lib/bundler/runtime.rb:76:in `each'
6: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bundler-2.0.1/lib/bundler/runtime.rb:81:in `block (2 levels) in require'
5: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:25:in `require'
4: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:36:in `rescue in require'
3: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:20:in `require_with_bootsnap_lfi'
2: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/loaded_features_index.rb:80:in `register'
1: from /Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `block in require_with_bootsnap_lfi'
/Users//.rbenv/versions/2.6.2/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require': cannot load such file -- tabler-rubygem (LoadError)
```

I think this error originates from your `require 'sass'` statement [in line 53 of the rubygem.rb](https://github.com/lightyrs/tabler-rubygem/blob/72c26b9745947bb03382d6f8eb9759b106a0eb59/lib/tabler/rubygem.rb#L53) file. Currently I use the following work around
```ruby
gem 'sass-rails', '~> 5.0.7', require: false
gem 'sassc-rails', '~> 2.1.0'
```
Do you have any idea why this isn't working?

Many thanks..!