Bump helm.sh/helm/v3 from 3.18.0 to 3.18.1 in /tests (#599)

Bumps [helm.sh/helm/v3](https://github.com/helm/helm) from 3.18.0 to 3.18.1.
- [Release notes](https://github.com/helm/helm/releases)
- [Commits](https://github.com/helm/helm/compare/v3.18.0...v3.18.1)

---
updated-dependencies:
- dependency-name: helm.sh/helm/v3
  dependency-version: 3.18.1
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

tests/go.mod

@@ -7,7 +7,7 @@ toolchain go1.24.1
 require (
 	github.com/onsi/ginkgo/v2 v2.23.4
 	github.com/onsi/gomega v1.37.0
-	helm.sh/helm/v3 v3.18.0
+	helm.sh/helm/v3 v3.18.1
 )
 
 require (