.github/workflows: update golangci-lint GitHub action for Go 1.16 support
.github/workflows: update golangci-lint GitHub action for Go 1.16 support

Bump the GH action and golangci-lint to latest versions for Go 1.16
support. Disable installation of Go from the GH action and reuse the one
already provided.

Signed-off-by: Tobias Klauser <9249c549618448e4c699e8032ba6c7f0d7fd4b7f@distanz.ch>

tklauser/cilium,michi-covalent/cilium,tgraf/cilium,tgraf/cilium,michi-covalent/cilium,tgraf/cilium,michi-covalent/cilium,tgraf/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,tgraf/cilium,tklauser/cilium,tgraf/cilium,cilium/cilium,michi-covalent/cilium,tklauser/cilium,cilium/cilium,tklauser/cilium,cilium/cilium,tklauser/cilium