v1.8.1

Reserve one Category for the privileged containers to use
ci: switch to go 1.16 final
label_test: nits on errors
label_test: use t.Skip
.pullapprove.yml: remove
ci: switch from travis to github actions
Makefile: rm golangci-lint install, GOPATH check
support mips64le architecture.
doc.go: remove outdated description about the build tag