Adjust modal border radius to match design spec

Set modal border radius to 0.25rem
With 16px default font size, should match the 4px from the design spec
Before this, it was the bootstrap default (0.3rem = 4.8px)

app/assets/stylesheets/framework/modal.scss

@@ -86,6 +86,10 @@ body.modal-open {
 .modal {
   background-color: $black-transparent;
+  .modal-content {
+    border-radius: 0.25rem;
+  }
+
   @include media-breakpoint-up(sm) {
     .modal-dialog {
       margin: 64px auto;