dev: don't build releases for plan9. some functionality is unavailable
dev: don't build releases for plan9. some functionality is unavailable

```
1 errors occurred:
--> plan9/386 error: exit status 2
Stderr: # github.com/fatih/color
../../fatih/color/color.go:17: undefined: isatty.IsTerminal
../../yuin/gopher-lua/iolib.go:286: undefined: syscall.WaitStatus
```

bmatsuo/lark,bmatsuo/lark