Bump isort, enable Cython package resorting

[charlesbluca]

With rapidsai/integration#286, the version of isort running on gpuCI will be bumped to 5.6.4, allowing us to enforce the sorting of packages in Cython (pyx, pxd) files. This PR intends to:

• Enable these checks in the gpuCI style script
• Enable Cython package resorting in the pre-commit hook
• Resort all the Cython files in this repo so they pass the newly enabled checks

[ajschmidt8]

rerun tests

[ajschmidt8]

rerun tests

[madsbk]

rerun tests

[madsbk]

rerun tests

[charlesbluca]

Just double checked and there aren't any changes that need to be made to the codebase on this PR - all hooks pass and this can be merged.

[galipremsagar]

@gpucibot merge

[ajschmidt8]

@gpucibot merge

[ajschmidt8]

@gpucibot merge

shoot. I think since this repo uses a different branch name format, it might be affecting the bot's merging capabilities. I'll have to look into this.

[ajschmidt8]

oh, actually the bot isn't enabled on this repo. I'll manually merge.

[galipremsagar]

@gpucibot merge

shoot. I think since this repo uses a different branch name format, it might be affecting the bot's merging capabilities. I'll have to look into this.

Thanks @ajschmidt8 !

[jakirkham]

Thanks AJ! 😄

Yeah we are doing things manually here. It's probably not worth the effort to change that as we want to upstream this work