build(deps): bump github.com/containernetworking/plugins

Bumps [github.com/containernetworking/plugins](https://github.com/containernetworking/plugins) from 1.1.1 to 1.2.0.
- [Release notes](https://github.com/containernetworking/plugins/releases)
- [Commits](https://github.com/containernetworking/plugins/compare/v1.1.1...v1.2.0)

---
updated-dependencies:
- dependency-name: github.com/containernetworking/plugins
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

vendor/github.com/vishvananda/netlink/link.go

@@ -1038,6 +1038,7 @@ type Iptun struct {
 	EncapType  uint16
 	EncapFlags uint16
 	FlowBased  bool
+	Proto      uint8
 }
 
 func (iptun *Iptun) Attrs() *LinkAttrs {