Removed unused third-party SCSS imports from app.scss.

app/application/resources/volt/scss/app.scss

@@ -23,10 +23,6 @@
 @import "bootstrap/scss/functions";
 @import "volt/variables";
 
-// Third party
-@import 'vanillajs-datepicker/sass/datepicker.scss';
-@import "chartist/dist/scss/chartist.scss";
-
 // Bootstrap
 @import "bootstrap/scss/variables";
 @import "bootstrap/scss/mixins";