Model saving is calling on git which causes an issue when the subprocess library is from the system

[sarthakpati]

Describe the bug
When the subprocess library is called from the system installation of python, git invocation does not work, since there is no git repo for the system python installation.

To Reproduce
Steps to reproduce the behavior:

1. Start GaNDLF training
2. See the following error:

$ > cat ${error_log}
[SNIP!]
  File "/geode2/home/u070/patis/BigRed200/projects/gandlf_mine/GANDLF/compute/training_loop.py", line 290, in training_loop
    save_model(
  File "/geode2/home/u070/patis/BigRed200/projects/gandlf_mine/GANDLF/utils/modelio.py", line 159, in save_model
    subprocess.check_output(["git", "rev-parse", "HEAD"])
  File "/N/soft/sles15/deeplearning/Python-3.10.10/Lib/subprocess.py", line 421, in check_output
    return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
  File "/N/soft/sles15/deeplearning/Python-3.10.10/Lib/subprocess.py", line 503, in run
    with Popen(*popenargs, **kwargs) as process:
  File "/N/soft/sles15/deeplearning/Python-3.10.10/Lib/subprocess.py", line 971, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "/N/soft/sles15/deeplearning/Python-3.10.10/Lib/subprocess.py", line 1847, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)

Expected behavior
The model saving should work.

Screenshots
N.A.

GaNDLF Version

0.0.17-dev

Desktop (please complete the following information):
N.A.

Additional context
This is seen for the IU BigRed cluster.

[scap3yvt]

I have fixed this, and will put a PR soon.