🎨(react) make eof stylesheets consistent

Some older tools misbehave if the last line of data
in a text file is not terminated with a newline.
It makes sure the last line was properly terminated.

packages/react/src/index.scss

@@ -16,4 +16,4 @@
 
 * {
   font-family: var(--c--theme--font--families--base);
-}
+}