🔧 Refactor toTitleCase method to handle consecutive whitespace correctly in both nullable and non-nullable string extensions

Closes #48

Author: esentis

lib/src/nullable_string_extensions.dart

@@ -812,7 +812,7 @@ extension MiscExtensionsNullable on String? {
       return this;
     }
 
-    var words = this!.trim().toLowerCase().split(' ');
+    var words = this!.trim().toLowerCase().split(RegExp(r'\s+'));
     for (var i = 0; i < words.length; i++) {
       words[i] = words[i].substring(0, 1).toUpperCase() + words[i].substring(1);
     }

lib/src/string_extensions.dart

@@ -781,7 +781,7 @@ extension MiscExtensionsNonNullable on String {
       return this;
     }
 
-    var words = this.trim().toLowerCase().split(' ');
+    var words = this.trim().toLowerCase().split(RegExp(r'\s+'));
     for (var i = 0; i < words.length; i++) {
       words[i] = words[i].substring(0, 1).toUpperCase() + words[i].substring(1);
     }

test/string_extensions_test.dart

@@ -57,6 +57,7 @@ void main() {
       expect(' '.toTitleCase, ' ');
       expect('  '.toTitleCase, '  ');
       expect(null.toTitleCase, null);
+      expect('title  case'.toTitleCase, 'Title Case');
     },
   );
   test(