chore(deps): bump sigs.k8s.io/structured-merge-diff/v6

Bumps [sigs.k8s.io/structured-merge-diff/v6](https://github.com/kubernetes-sigs/structured-merge-diff) from 6.3.2 to 6.4.0.
- [Release notes](https://github.com/kubernetes-sigs/structured-merge-diff/releases)
- [Changelog](https://github.com/kubernetes-sigs/structured-merge-diff/blob/master/RELEASE.md)
- [Commits](kubernetes-sigs/structured-merge-diff@v6.3.2...v6.4.0)

---
updated-dependencies:
- dependency-name: sigs.k8s.io/structured-merge-diff/v6
  dependency-version: 6.4.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

go.mod

@@ -52,7 +52,7 @@ require (
 	knative.dev/serving v0.48.2
 	sigs.k8s.io/controller-runtime v0.23.3
 	sigs.k8s.io/gateway-api v1.5.1
-	sigs.k8s.io/structured-merge-diff/v6 v6.3.2
+	sigs.k8s.io/structured-merge-diff/v6 v6.4.0
 )
 
 require (

go.sum

@@ -505,8 +505,8 @@ sigs.k8s.io/json v0.0.0-20250730193827-2d320260d730 h1:IpInykpT6ceI+QxKBbEflcR5E
 sigs.k8s.io/json v0.0.0-20250730193827-2d320260d730/go.mod h1:mdzfpAEoE6DHQEN0uh9ZbOCuHbLK5wOm7dK4ctXE9Tg=
 sigs.k8s.io/randfill v1.0.0 h1:JfjMILfT8A6RbawdsK2JXGBR5AQVfd+9TbzrlneTyrU=
 sigs.k8s.io/randfill v1.0.0/go.mod h1:XeLlZ/jmk4i1HRopwe7/aU3H5n1zNUcX6TM94b3QxOY=
-sigs.k8s.io/structured-merge-diff/v6 v6.3.2 h1:kwVWMx5yS1CrnFWA/2QHyRVJ8jM6dBA80uLmm0wJkk8=
-sigs.k8s.io/structured-merge-diff/v6 v6.3.2/go.mod h1:M3W8sfWvn2HhQDIbGWj3S099YozAsymCo/wrT5ohRUE=
+sigs.k8s.io/structured-merge-diff/v6 v6.4.0 h1:qmp2e3ZfFi1/jJbDGpD4mt3wyp6PE1NfKHCYLqgNQJo=
+sigs.k8s.io/structured-merge-diff/v6 v6.4.0/go.mod h1:M3W8sfWvn2HhQDIbGWj3S099YozAsymCo/wrT5ohRUE=
 sigs.k8s.io/yaml v1.2.0/go.mod h1:yfXDCHCao9+ENCvLSE62v9VSji2MKu5jeNfTrofGhJc=
 sigs.k8s.io/yaml v1.6.0 h1:G8fkbMSAFqgEFgh4b1wmtzDnioxFCUgTZhlbj5P9QYs=
 sigs.k8s.io/yaml v1.6.0/go.mod h1:796bPqUfzR/0jLAl6XjHl3Ck7MiyVv8dbTdyT3/pMf4=