debian/control: Add Build-Depends

Add Build-Depends:
  golang-github-opencontainers-specs-dev (<< 1.0.0~rc2)
Since golang-github-opencontainers-specs-dev in sid is 1.0.0~rc2
Which has FTBFS issue. We need to use the fixed version in
stretch, which is 1.0.0~rc1.

Closes: #858250