chore(deps): update dependency kubernetes-sigs/external-dns to v1.21.1

[renovate]

This PR contains the following updates:

Package	Update	Change
kubernetes-sigs/external-dns	minor	1.20.0 → 1.21.1

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Release Notes

kubernetes-sigs/external-dns (kubernetes-sigs/external-dns)

v1.21.1

Compare Source

Added

• Add value .sourceNamespace to watch a namespace which is different from the one that external-dns is installed into when .namespaced is true. (#​6297) @​jplitza
• Add option to enable Gateway API ListenerSet support. (#​6381) @​speer
• Add support for bool in extraArgs. (#​6179) @​farodin91
• Add value .namespaceOverride to render chart resources into a namespace different from the release namespace, for subchart installs that want their own namespace. (#​6389) @​alliasgher

Changed

• Update ExternalDNS OCI image version to v0.21.0. (#​6354) @​vflaux

Fixed

• Avoid creating cluster-scoped RBAC for Gateway API sources when running namespaced with gatewayNamespace set. Namespace listing permissions are now only added when gatewayNamespace is unset. (#​5843) @​TobyTheHutt
• Ensure container arguments are passed in as strings (#​6264) @​KhooHaoYit
• Ensure container arguments are passed in as strings when extraArgs is a map (#​6284) @​vflaux

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