Specify type of stream_reader_factory

[hf-kklein]

Fixes mypy warning

aioresponses\compat.py:31: error: All conditional function variants must have identical signatures [misc]

[codecov-commenter]

Codecov Report

Merging #208 (b0786c4) into master (b8393e7) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #208      +/-   ##
==========================================
+ Coverage   95.75%   95.77%   +0.01%     
==========================================
  Files           3        3              
  Lines         283      284       +1     
==========================================
+ Hits          271      272       +1     
  Misses         12       12              

Impacted Files	Coverage Δ
aioresponses/compat.py	75.60% <100.00%> (+0.60%)	⬆️

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[marcinsulikowski]

If mypy reports that error: All conditional function variants must have identical signatures [misc], wouldn't it be better to just add correct type annotations to both variants of stream_reader_factory?

if AIOHTTP_VERSION >= parse_version('3.0.0'):
    from aiohttp.client_proto import ResponseHandler

    def stream_reader_factory(
        loop: Optional[asyncio.AbstractEventLoop] = None
    ) -> StreamReader:
        protocol = ResponseHandler(loop=loop)
        return StreamReader(protocol, limit=2 ** 16, loop=loop)

else:

    def stream_reader_factory(
        loop: Optional[asyncio.AbstractEventLoop] = None
    ) -> StreamReader:
        return StreamReader()

[marcinsulikowski]

Actually, this whole if statement and two versions of stream_reader_factory are not needed, see #223

[hf-kklein]

You're right. Merging #224 would make this PR obsolete :)