Avoid trailing commas for parenthesized SCSS scalars (#19091)

Co-authored-by: fisker Cheung <lionkay@gmail.com>

changelog_unreleased/scss/19091.md

@@ -0,0 +1,22 @@
+#### Avoid adding trailing comma to parenthesized scalars (#19091 by @cyphercodes)
+
+<!-- prettier-ignore -->
+```scss
+// Input
+.a { background-color: rgba($color: (#808080), $alpha: 0.9); }
+
+// Prettier stable
+.a {
+  background-color: rgba(
+    $color: (
+      #808080,
+    ),
+    $alpha: 0.9
+  );
+}
+
+// Prettier main
+.a {
+  background-color: rgba($color: (#808080), $alpha: 0.9);
+}
+```