Version check for open_pdks and skywater-pdk does not work with volare pdk installation

[d-m-bailey]

Non fatal error that fails to check the open_pdks and skywater-pdk versions.

With a non volare installation, the open_pdks and skywater-pdk repos are available for commit checking. From mpw_precheck.py

    with open(pdks_info_path, 'w') as pdks_info:
        try:
            pdk_dir = f"{precheck_config['pdk_path'].parent}/%s"
            open_pdks_v_cmd = ['git', '-C', pdk_dir % 'open_pdks', 'rev-parse', '--verify', 'HEAD']
            skywater_pdk_v_cmd = ['git', '-C', pdk_dir % 'skywater-pdk', 'rev-parse', '--verify', 'HEAD']
            open_pdks_version = subprocess.check_output(open_pdks_v_cmd, encoding='utf-8').rstrip()
            skywater_pdk_version = subprocess.check_output(skywater_pdk_v_cmd, encoding='utf-8').rstrip()
            pdks_info.write(f"Open PDKs {open_pdks_version}\n")
            pdks_info.write(f"Skywater PDK {skywater_pdk_version}")
            logging.info(f"{{{{PDKs Info}}}} PDK: {precheck_config['pdk_path'].name} | Open PDKs: {open_pdks_version} | Skywater PDK: {skywater_pdk_version}")

However, the volare installation does not contain the repos, so a non-fatal error results.

{{Tools Info}} KLayout: v0.27.10 | Magic: v8.3.315
fatal: cannot change to '<PDK_ROOT>/open_pdks': No such file or directory
MPW Precheck failed to get Open PDKs & Skywater PDK versions: Command '['git', '-C', '<PDK_ROOT>/open_pdks', 'rev-parse', '--verify', 'HEAD']' returned non-zero exit status 128.

The open_pdks commit is available in $PDK_PATH/SOURCES, but I couldn't find the skywater-pdks commit anywhere.