Freeze the jekyll-sass-converter version

The reason is the previously mentioned problem. [1] [2]

[1]: mmistakes/minimal-mistakes#4054
[2]: jekyll/jekyll-sass-converter#145 (comment)

Author: torrocus

Gemfile

@@ -9,7 +9,7 @@ gem 'jekyll-include-cache'
 gem 'jekyll-pwa-workbox'
 gem 'jekyll-redirect-from'
 gem 'jekyll-remote-theme'
-gem 'jekyll-sass-converter', '~> 2.2'
+gem 'jekyll-sass-converter', '2.2'
 gem 'liquid'
 gem 'minimal-mistakes-jekyll'
 gem 'webrick'

Gemfile.lock

@@ -154,7 +154,7 @@ DEPENDENCIES
   jekyll-pwa-workbox
   jekyll-redirect-from
   jekyll-remote-theme
-  jekyll-sass-converter (~> 2.2)
+  jekyll-sass-converter (= 2.2)
   liquid
   minimal-mistakes-jekyll
   webrick