Fix fingerprinting import issue

[J-CPelletier]

Goal

The goal of this PR is to do the changes explained here: #311 (comment) and to solve #316

I do this by copying the Scrapy code for fingerprinting to keep backwards compatibility, and I also added a new fingerprinter using the newer function.

[J-CPelletier]

After testing the master branch on my end with this change to the setup.py to allow for things to run like before:
install_requires=['scrapy==2.11.2', 'six'],
I see that most integrations tests fail in the exact same way that they do in this PR. Do we want to fix them in this PR or in another one? This seems more like a blocker to us being able to release a working version in this situation.

[Gallaecio]

Do we want to fix them in this PR or in another one?

I think whatever works best for you.

[J-CPelletier]

I think whatever works best for you.

The integration tests seem to working in the CI, although I haven't been able to reproduce it locally (through the commands directly or using act). The issue had to do with setting up the MockServer and getting Connection Refused in the test, but if it works in the Actions it's not a big deal.

This should now be ready for code reviews.

[Gallaecio]

Looks good to me. The only thing I think is missing is updating the README accordingly, to replace the old configuration instructions with the new ones.

[J-CPelletier]

I just did the fixes you requested, let me know if I missed something!

[wRAR]

TypeError: SplashRequestFingerprinter.__init__() missing 1 required positional argument: 'crawler'

[J-CPelletier]

TypeError: SplashRequestFingerprinter.__init__() missing 1 required positional argument: 'crawler'

I just fixed that, the tests should now pass

[fliot]

This CR is a great update, thanks !
+1