Remove unnecessary process wait on MacOS (issue #1523)

[cedel1]

Remove process.communicate() in MacOS causing wait for subprocess even when the subprocess results were not used.

[cedel1]

Hmm, I am surprised by the unrelated codecov check failure (especially since that part wasn't changed for quite some time, it fails on master and tests in previous PRs passed. Version changes?

[codecov-commenter]

Codecov Report

Patch coverage is 89.91% of modified lines.

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Files Changed	Coverage
httpie/output/ui/man_pages.py	0.00%
httpie/output/ui/rich_utils.py	0.00%
tests/test_binary.py	ø
tests/test_defaults.py	ø
tests/test_output.py	ø
tests/test_parser_schema.py	ø
tests/test_plugins_cli.py	ø
tests/test_redirects.py	ø
tests/test_regressions.py	ø
tests/test_sessions.py	ø
... and 90 more

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