Fix the description of some tests for SassNumber (#1463)

123/5 does not produce an integer.

test/dart_api/value/number_test.dart

@@ -311,7 +311,7 @@ void main() {
     });
   });
 
-  group("an integer with numerator and denominator units", () {
+  group("a number with numerator and denominator units", () {
     late SassNumber value;
     setUp(() => value = parseValue("123px / 5ms") as SassNumber);