Simpler mechanism for embedding SRI hashes

Remove the build-time dependency on Python, the sri_map is now
generated via a small Go script.
3 jobs for better-login in 2 minutes and 41 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build Pkgsrc
passed #13982
build_pkgsrc:stretch

00:00:11

 
  Build Pkg
passed #13983
amd64
build_pkg:stretch:amd64

00:00:31

passed #13984
arm64
build_pkg:stretch:arm64

00:02:29