fix(asgi): Incomplete, add finally to stream close

[dimucciojonathan]

Summary of Changes

@vytas7

• finally clause was added to falcon/asgi/app.py, so that the stream is closed even when an exception occurs.
• There are now two failed assertions in tests/asgi/test_hello_asgi.py, which are related to closing of the file. Assistance / guidance from an expert is needed.
• No tests have been drafted yet, since I haven't been able to pass the current tests yet.

Related Issues

1943

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[dimucciojonathan]

Error Message:

================================================= short test summary info ================================================= FAILED tests/asgi/test_hello_asgi.py::TestHelloWorld::test_filelike_closing_aiofiles - assert False FAILED tests/asgi/test_hello_asgi.py::TestHelloWorld::test_filelike_closing[DataReader-True] - assert False ========================== 2 failed, 3088 passed, 168 skipped, 16 warnings in 192.20s (0:03:12) =========================== ERROR: InvocationError for command /Users/a1425/Documents/python-files/falcon-repo/falcon/.tox/py38/bin/coverage run -m pytest tests (exited with code 1)

[codecov[bot]]

Codecov Report

Merging #1948 (7a355e1) into master (e255bff) will not change coverage. The diff coverage is n/a.

@@            Coverage Diff            @@
##            master     #1948   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           63        63           
  Lines         6610      6610           
  Branches      1067      1067           
=========================================
  Hits          6610      6610           

Impacted Files	Coverage Δ
falcon/asgi/app.py	100.00% <ø> (ø)

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