Remove deprecated ~ from imports

Ref: https://webpack.js.org/loaders/sass-loader/#resolving-import-at-rules

app/javascript/stylesheets/bootstrap-variables.scss

@@ -6,4 +6,4 @@ $rails-red: #e00000 !default;
 
 $primary: $rails-red !default;
 
-@import "~bootstrap/scss/variables";
+@import "bootstrap/scss/variables";

app/javascript/stylesheets/bootstrap.scss

@@ -1,46 +1,46 @@
-/* Full copy of ~bootstrap/scss/bootstrap.scss */
+/* Full copy of bootstrap/scss/bootstrap.scss */
 
 // Configuration
-@import "~bootstrap/scss/functions";
+@import "bootstrap/scss/functions";
 @import "bootstrap-variables";
-@import "~bootstrap/scss/mixins";
-@import "~bootstrap/scss/utilities";
+@import "bootstrap/scss/mixins";
+@import "bootstrap/scss/utilities";
 
 // Layout & components
-@import "~bootstrap/scss/root";
-@import "~bootstrap/scss/reboot";
-@import "~bootstrap/scss/type";
-@import "~bootstrap/scss/images";
-@import "~bootstrap/scss/containers";
-@import "~bootstrap/scss/grid";
-@import "~bootstrap/scss/tables";
-@import "~bootstrap/scss/forms";
-@import "~bootstrap/scss/buttons";
-@import "~bootstrap/scss/transitions";
-@import "~bootstrap/scss/dropdown";
-@import "~bootstrap/scss/button-group";
-@import "~bootstrap/scss/nav";
-@import "~bootstrap/scss/navbar";
-@import "~bootstrap/scss/card";
-@import "~bootstrap/scss/accordion";
-@import "~bootstrap/scss/breadcrumb";
-@import "~bootstrap/scss/pagination";
-@import "~bootstrap/scss/badge";
-@import "~bootstrap/scss/alert";
-@import "~bootstrap/scss/progress";
-@import "~bootstrap/scss/list-group";
-@import "~bootstrap/scss/close";
-@import "~bootstrap/scss/toasts";
-@import "~bootstrap/scss/modal";
-@import "~bootstrap/scss/tooltip";
-@import "~bootstrap/scss/popover";
-@import "~bootstrap/scss/carousel";
-@import "~bootstrap/scss/spinners";
-@import "~bootstrap/scss/offcanvas";
-@import "~bootstrap/scss/placeholders";
+@import "bootstrap/scss/root";
+@import "bootstrap/scss/reboot";
+@import "bootstrap/scss/type";
+@import "bootstrap/scss/images";
+@import "bootstrap/scss/containers";
+@import "bootstrap/scss/grid";
+@import "bootstrap/scss/tables";
+@import "bootstrap/scss/forms";
+@import "bootstrap/scss/buttons";
+@import "bootstrap/scss/transitions";
+@import "bootstrap/scss/dropdown";
+@import "bootstrap/scss/button-group";
+@import "bootstrap/scss/nav";
+@import "bootstrap/scss/navbar";
+@import "bootstrap/scss/card";
+@import "bootstrap/scss/accordion";
+@import "bootstrap/scss/breadcrumb";
+@import "bootstrap/scss/pagination";
+@import "bootstrap/scss/badge";
+@import "bootstrap/scss/alert";
+@import "bootstrap/scss/progress";
+@import "bootstrap/scss/list-group";
+@import "bootstrap/scss/close";
+@import "bootstrap/scss/toasts";
+@import "bootstrap/scss/modal";
+@import "bootstrap/scss/tooltip";
+@import "bootstrap/scss/popover";
+@import "bootstrap/scss/carousel";
+@import "bootstrap/scss/spinners";
+@import "bootstrap/scss/offcanvas";
+@import "bootstrap/scss/placeholders";
 
 // Helpers
-@import "~bootstrap/scss/helpers";
+@import "bootstrap/scss/helpers";
 
 // Utilities
-@import "~bootstrap/scss/utilities/api";
+@import "bootstrap/scss/utilities/api";