code objects analysis replaced with inspect

[Trizalio]

multi_cached works incorrectly with decorated functions, called with keys_from_attr value passed as positional argument, example:

import asyncio
import functools
from typing import List, Dict

from aiocache import multi_cached


async def foo(ids: List[int]) -> Dict[int, int]:
    return {id_: id_ ** 2 for id_ in ids}


def simple_decorator(f):
    @functools.wraps(f)
    async def wrapper(*args, **kwargs):
        return await f(*args, **kwargs)
    return wrapper


cached_foo = multi_cached("ids", namespace="main")(foo)
cached_wrapped_foo = multi_cached("ids", namespace="main")(simple_decorator(foo))


async def amain():
    await cached_foo(ids=[1])  # ok
    await cached_foo([1])  # ok
    await cached_wrapped_foo(ids=[1])  # ok
    await cached_wrapped_foo([1])  # EXCEPTION

if __name__ == "__main__":
    asyncio.run(amain())

This problem's reason is analysis of code object of function passed to multi_cached decorator.
To properly get arguments from function decorated with functools.wraps, it's required to get signature of inner function. Which can be accessed by __wrapped__ attribute, or by inspect.signature function, which goes recursively through __wrapped__ attributes till core function.
I suggest to used inspect.signature instead of direct code obejects inteaction.

[codecov]

Codecov Report

Merging #487 into master will decrease coverage by 0.60%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #487      +/-   ##
==========================================
- Coverage   99.13%   98.52%   -0.61%     
==========================================
  Files          13       11       -2     
  Lines        1043      952      -91     
  Branches      116      104      -12     
==========================================
- Hits         1034      938      -96     
  Misses          9        9              
- Partials        0        5       +5     

Impacted Files	Coverage Δ
aiocache/decorators.py	94.03% <100.00%> (-5.97%)	⬇️
aiocache/serializers/serializers.py	95.08% <0.00%> (-0.24%)	⬇️
aiocache/base.py	100.00% <0.00%> (ø)
aiocache/factory.py	100.00% <0.00%> (ø)
aiocache/backends/redis.py	100.00% <0.00%> (ø)
aiocache/backends/memory.py	100.00% <0.00%> (ø)
aiocache/backends/memcached.py	100.00% <0.00%> (ø)
aiocache/__init__.py
aiocache/plugins.py

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[Trizalio]

i'm quite new in coverage checks, can someone tell me, how is serializers.py file affected by my commit?

[argaen]

Some tests are failing so it can be because of this as a side effect. Don't check coverage until the build passes

[Dreamsorcerer]

Hey, sorry for the delay, if you can merge master and get this running again, then we can look at merging this.

If I understand correctly, the test is only affected by function signatures, so you should also move the test to tests/ut/test_decorators.py and use a mock_cache instead.