Flannel - v0.21.0

What's Changed

• Updated documentation by @rbrtbnfgl in https://github.com/flannel-io/flannel/pull/1687
• Implement MultiClusterCIDR feature in flannel by @thomasferrandiz in https://github.com/flannel-io/flannel/pull/1658
• adapt iptables_windows.go to the new API by @thomasferrandiz in https://github.com/flannel-io/flannel/pull/1691
• Organize project code following modern go best practices by @manuelbuil in https://github.com/flannel-io/flannel/pull/1690
• Remove vendor dir and update golang.org/x/net by @manuelbuil in https://github.com/flannel-io/flannel/pull/1692
• remove cpu and memory limits from manifests by @thomasferrandiz in https://github.com/flannel-io/flannel/pull/1694
• docs: update docs for etcd v3 api by @sejongk in https://github.com/flannel-io/flannel/pull/1697
• Use k3s to do the end to end tests of flannel on k8s by @thomasferrandiz in https://github.com/flannel-io/flannel/pull/1689
• Backend docs update by @rbrtbnfgl in https://github.com/flannel-io/flannel/pull/1705
• Updated docker registry and release action by @rbrtbnfgl in https://github.com/flannel-io/flannel/pull/1706
• Upgrade base images to fix CVE by @thomasferrandiz in https://github.com/flannel-io/flannel/pull/1708
• fix: old document with wrong path :tea: by @mrnonz in https://github.com/flannel-io/flannel/pull/1710
• Add missing EnableIPv4 config keyword to docs by @agowa338 in https://github.com/flannel-io/flannel/pull/1711

New Contributors

• @sejongk made their first contribution in https://github.com/flannel-io/flannel/pull/1697
• @mrnonz made their first contribution in https://github.com/flannel-io/flannel/pull/1710
• @agowa338 made their first contribution in https://github.com/flannel-io/flannel/pull/1711

Full Changelog: https://github.com/flannel-io/flannel/compare/v0.20.2...v0.21.0