Add additional test for regex format

Author: OptimumCode

src/commonTest/kotlin/io/github/optimumcode/json/schema/assertions/general/format/JsonSchemaRegexFormatValidationTest.kt

@@ -0,0 +1,20 @@
+package io.github.optimumcode.json.schema.assertions.general.format
+
+import io.kotest.core.spec.style.FunSpec
+
+class JsonSchemaRegexFormatValidationTest : FunSpec() {
+  init {
+    formatValidationTestSuite(
+      format = "regex",
+      validTestCases =
+        listOf(
+          "",
+          "(?=test\\s)",
+        ),
+      invalidTestCases =
+        listOf(
+          TestCase("(test", "missing brackets"),
+        ),
+    )
+  }
+}