OpenROAD: Fix version string in binary

[ubfx]

Currently git describe is failing within the OpenROAD build which leads to the version number compiled into the binary falling back to a hash which doesn't work well for version checking.

https://github.com/hdl/conda-eda/actions/runs/8012258777/job/21887187187#step:5:2091

  23:23:44 | CMake Warning at CMakeLists.txt:98 (message):
  23:23:44 |   OpenROAD git describe failed, using sha1 instead

The reson seems to be that cmake is called with -DCMAKE_FIND_ROOT_PATH such that find_package(Git) fails. Easiest solution seems to be to just add git to the build requirements, which this patch does. Alternatively we could probably pass GIT_EXECUTABLE to cmake.

Fix #365

[ubfx]

Looks like this worked 🎉

https://github.com/hdl/conda-eda/actions/runs/8015700461/job/21896297577?pr=374#step:5:2239

06:57:23 | -- OpenROAD version: 2.0-12327-g933ae804c

cc @proppy

[proppy]

Thanks for figuring that out!