CLN: Cython warnings for type declartions

[alimcmaster1]

warning: pandas/_libs/internals.pyx:144:29: Strings should no longer be used for type declarations. Use 'cython.int' etc. directly.
warning: pandas/_libs/internals.pyx:147:32: Strings should no longer be used for type declarations. Use 'cython.int' etc. directly.
warning: pandas/_libs/internals.pyx:188:28: Strings should no longer be used for type declarations. Use 'cython.int' etc. directly.

(Against cython master)

[WillAyd]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[WillAyd]

Can you merge master again; doesn't look like all the checks have run. Chance this might not work with Py36 but will see in CI (maybe PEP 563 is a pre-cursor)

[alimcmaster1]

@WillAyd thanks - all checks have run now

[WillAyd]

lgtm. I suppose this differs slightly from Python annotation requirements before PEP 563 was implemented but I don't have any objection unless @scoder knows any better

[scoder]

Hmm … yeah, that's PEP-563. I think it's really best to move forward with this and use real types in annotations instead of string names.

[jreback]

thanks @alimcmaster1