build(deps): bump golang.org/x/net in /conformance/echo-basic

Bumps [golang.org/x/net](https://github.com/golang/net) from 0.20.0 to 0.21.0.
- [Commits](golang/net@v0.20.0...v0.21.0)

---
updated-dependencies:
- dependency-name: golang.org/x/net
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

conformance/echo-basic/go.mod

@@ -2,6 +2,6 @@ module sigs.k8s.io/gateway-api/conformance/echo-basic
 
 go 1.21
 
-require golang.org/x/net v0.20.0
+require golang.org/x/net v0.21.0
 
 require golang.org/x/text v0.14.0 // indirect

conformance/echo-basic/go.sum

@@ -1,4 +1,4 @@
-golang.org/x/net v0.20.0 h1:aCL9BSgETF1k+blQaYUBx9hJ9LOGP3gAVemcZlf1Kpo=
-golang.org/x/net v0.20.0/go.mod h1:z8BVo6PvndSri0LbOE3hAn0apkU+1YvI6E70E9jsnvY=
+golang.org/x/net v0.21.0 h1:AQyQV4dYCvJ7vGmJyKki9+PBdyvhkSd8EIx/qb0AYv4=
+golang.org/x/net v0.21.0/go.mod h1:bIjVDfnllIU7BJ2DNgfnXvpSvtn8VRwhlsaeUTyUS44=
 golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
 golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=