Add bool test

Author: martijn00

test/src/numeric/between_validator_test.dart

@@ -7,6 +7,23 @@ void main() {
   final String customErrorMessage = faker.lorem.sentence();
 
   group('BetweenValidator -', () {
+    group('bool', () {
+      test('should return errorText when type is invalid', () {
+        // Arrange
+        const num min = 5;
+        const num max = 10;
+        final BetweenValidator<bool> validator =
+            BetweenValidator<bool>(min, max, errorText: customErrorMessage);
+        const bool value = true;
+
+        // Act
+        final String? result = validator.validate(value);
+
+        // Assert
+        expect(result, equals(customErrorMessage));
+      });
+    });
+
     group('num', () {
       test('should return null if the value is exactly at the minimum boundary',
           () {