Update build_board_info.py to sh module 2.0.0

[Neradoc]

Due to today's release of the sh python module 2.0.0, the CI fails in build_board_info.py
see https://github.com/adafruit/circuitpython/actions/runs/4140380646

Run python3 -u build_release_files.py
Traceback (most recent call last):
  File "/home/runner/work/circuitpython/circuitpython/tools/build_release_files.py", line 30, in <module>
    sha, version = build_info.get_version_info()
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/runner/work/circuitpython/circuitpython/tools/build_board_info.py", line 61, in get_version_info
    sha = git("rev-parse", "--short", "HEAD").stdout.decode("utf-8")
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'str' object has no attribute 'stdout'
Error: Process completed with exit code 1.

Because it now returns a string:
https://github.com/amoffat/sh/blob/develop/MIGRATION.md#return-value-now-a-true-string
Adabot doesn't seem to need to be updated since it uses the _out = ... argument (with StringIO).

[microdev1]

LGTM! Thanks @Neradoc.

[dhalbert]

Tagged for backporting to 8.0.x

[dhalbert]

Backported to 8.0.x as part of #7566.