chore(dependabot): bump istio.io/client-go from 1.20.2 to 1.21.0 (#1395)

Bumps [istio.io/client-go](https://github.com/istio/client-go) from 1.20.2 to 1.21.0.
- [Commits](istio/client-go@1.20.2...1.21.0)

---
updated-dependencies:
- dependency-name: istio.io/client-go
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

go.mod

@@ -30,7 +30,7 @@ require (
 
 require (
 	istio.io/api v1.21.0
-	istio.io/client-go v1.20.2
+	istio.io/client-go v1.21.0
 )
 
 require (

go.sum

@@ -2417,8 +2417,8 @@ inet.af/netaddr v0.0.0-20230525184311-b8eac61e914a h1:1XCVEdxrvL6c0TGOhecLuB7U9z
 inet.af/netaddr v0.0.0-20230525184311-b8eac61e914a/go.mod h1:e83i32mAQOW1LAqEIweALsuK2Uw4mhQadA5r7b0Wobo=
 istio.io/api v1.21.0 h1:K/+8GrGoupyCBa7/a/znnEzg34Qk0l1Rpki1PrtSVJY=
 istio.io/api v1.21.0/go.mod h1:TFCMUCAHRjxBv1CsIsFCsYHPHi4axVI4vdIzVr8eFjY=
-istio.io/client-go v1.20.2 h1:FL99qw5f5W+QFPHutLpGOoPmoKgLwNFrGCEemAvLm00=
-istio.io/client-go v1.20.2/go.mod h1:mub0nwPDAj98cjns7KYLzbvDk0Fg9rx0k2o+KZ4UIUY=
+istio.io/client-go v1.21.0 h1:Fr4Tcnmdk3SOXoeeyHzCgpKfTWVgkeuIYm7tRdARo5A=
+istio.io/client-go v1.21.0/go.mod h1:xFI6wdIPsXqUfE1P/sae1ImFN3KXcYCjKn1S24coFZI=
 k8s.io/api v0.20.1/go.mod h1:KqwcCVogGxQY3nBlRpwt+wpAMF/KjaCc7RpywacvqUo=
 k8s.io/api v0.20.4/go.mod h1:++lNL1AJMkDymriNniQsWRkMDzRaX2Y/POTUi8yvqYQ=
 k8s.io/api v0.20.6/go.mod h1:X9e8Qag6JV/bL5G6bU8sdVRltWKmdHsFUGS3eVndqE8=