fix: Fixed Illegal RegExp in Safari in 3.0.0-beta.1 and beta.2 (#1444)

Author: nambiarAswathi

lib/src/processing/whitespace.dart

@@ -226,8 +226,7 @@ class WhitespaceProcessing {
   /// (4) Replace any instances of two or more spaces with a single space.
   static String _removeUnnecessaryWhitespace(String text) {
     return text
-        .replaceAll(RegExp(r" *(?=\n)"), "")
-        .replaceAll(RegExp(r"(?<=\n) *"), "")
+        .replaceAll(RegExp(r" *\n *"), "\n")
         .replaceAll("\n", " ")
         .replaceAll("\t", " ")
         .replaceAll(RegExp(r" {2,}"), " ");