Fix a warning with getaddrinfo while compiling

[aiomaster]

add netgo to the build to fix this ugly warning:

/tmp/go-link-148332811/000004.o: In function `_cgo_f7895c2c5a3a_C2func_getaddrinfo':                                                                                                        
/tmp/go-build/cgo-gcc-prolog:46: warning: Using 'getaddrinfo' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking

Interestingly the Image size decreases with that fix by some KB.

I got the idea from here: https://github.com/opencontainers/runc/pull/1577

[PierreZ]

Thanks a lot for your contribution ❤️