`isEqualToIgnoringGivenProperties` does not check private fields

```kotlin
data class Obj(val publicStr: String, private val privateStr: String)

@Test
fun t() {
    val obj1 = Obj("public", "private1")
    val obj2 = Obj("public", "private2")

    assertThat(obj1).isEqualToIgnoringGivenProperties(obj2, MyClass::publicStr)
}
```

This test results in successful assertion, despite that private fields values is different.

assertkVer: 0.28.1