feat: Add type hints to stream module

[copalco]

Summary of Changes

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[CaselIT]

nice work, thanks!

[codecov]

Codecov Report

Merging #2166 (e2554f2) into master (0c68df3) will not change coverage.
The diff coverage is 100.00%.

❗ Current head e2554f2 differs from pull request most recent head 54b427a. Consider uploading reports for the commit 54b427a to get more accurate results

@@            Coverage Diff            @@
##            master     #2166   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           62        62           
  Lines         6830      6833    +3     
  Branches      1098      1098           
=========================================
+ Hits          6830      6833    +3     

Files Changed	Coverage Δ
falcon/stream.py	100.00% <100.00%> (ø)

[vytas7]

LGTM bar CI failures (and one cosmetic nitpick).

We normally don't merge with failing CI, so that ASGI tutorial error needs to be addressed separately assuming it is not caused by this PR. I can take a look at it. But the import grouping failure does seem to be introduced by this changeset.

[vytas7]

LGTM, thanks for this improvement!
(Particularly appreciated as typing ain't my forte 😅)