Failed test on hash.antisymmetry

https://github.com/typelevel/case-insensitive/actions/runs/18392877504/job/52406578075?pr=506

failing seed for hash.antisymmetry eq is pybM17lbc1HucUvnX921l2fH7SmLkpiyFXZtof-nd6E=
==> X org.typelevel.ci.CIStringSuite.Hash[CIString]: hash.antisymmetry eq 0.014s munit.FailException: tests/shared/src/test/scala/org/typelevel/ci/CIStringSuite.scala:212
211:  checkAll("Order[CIString]", OrderTests[CIString].order)
212:  checkAll("Hash[CIString]", HashTests[CIString].hash)
213:  checkAll("LowerBounded[CIString]", LowerBoundedTests[CIString].lowerBounded)

Failing seed: 8xWnjwz7hjrhK0LI9xkRmVGreER0YjXs0SvofK4suRD=
You can reproduce this failure by adding the following override to your suite:

  override def scalaCheckInitialSeed = "8xWnjwz7hjrhK0LI9xkRmVGreER0YjXs0SvofK4suRD="

Falsified after 1 passed tests.
> Labels of failing property: 
Expected: true
Received: false
> ARG_0: ϑ
> ARG_1: ϴ
> ARG_2: <function1>

Start with tests/shared/src/test/scala/org/typelevel/ci/CIStringSuite.scala at the HashTests check on line 212, using the reported ScalaCheck seed to reproduce the failure. Investigate the hash and equality behavior for the Greek characters ϑ and ϴ. Done means the reproducible property test passes without breaking the existing CIString hash laws.