Check for stdout/stderr in case file descriptor is closed

[julien-lecomte]

Summary of changes

File descrptors may be closed when using pipx, such is a case when using the bash specific file redirections clauses >&- and/or "2&-`

Test plan

Before:

$ pipx install bumpversion2 >&-
Traceback (most recent call last):
  File "/home/julien/.local/bin/pipx", line 5, in <module>
    from pipx.main import cli
  File "/home/julien/.local/pipx/venvs/pipx/lib/python3.11/site-packages/pipx/main.py", line 22, in <module>
    from pipx import commands, constants, paths
  File "/home/julien/.local/pipx/venvs/pipx/lib/python3.11/site-packages/pipx/commands/__init__.py", line 3, in <module>
    from pipx.commands.inject import inject
  File "/home/julien/.local/pipx/venvs/pipx/lib/python3.11/site-packages/pipx/commands/inject.py", line 9, in <module>
    from pipx.colors import bold
  File "/home/julien/.local/pipx/venvs/pipx/lib/python3.11/site-packages/pipx/colors.py", line 9, in <module>
    PRINT_COLOR = sys.stdout.isatty()
                  ^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'isatty'