---- 8< ----
pygolang: Always use git checkout for both release and development version

Similarly to wendelin.core (see ad34ff4a "wendelin.core: Always use git checkout for both release and development version") let's switch pygolang to install via git checkout for both release and tests.

This way we avoid dependency on pypi and will be able to do minor updates without doing bigger to-pypi releases. Always using git checkout also helps security a bit because we remove reliance on trust to tarball received from pypi.

/cc @jerome, @kazuhiko

---- 8< ----
pygolang: v↑ 0.1 -> 0.1-69-g044deb35

Upgrading pygolang in the context of SlapOS brings in some minor speedup and fixes, but is mostly needed for ors-amarisoft software release due to fix for a memory leak and optimized timers:

pygolang@2ec5e96b
pygolang@044deb35

The full list of the changes is below:

pygolang@pygolang-0.1...pygolang-0.1-69-g044deb35

/cc @jerome
/cc ORS team (@jhuge, @lu.xu, @tomo, @xavier_thompson, @Daetalus)