update fsspec to 2021.06.0

[awaelchli]

What does this PR do?

Usual business. Dependency releases new update and our CI goes down.
Gotta tweak some numbers to keep the machine running and heads attached.

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[codecov]

Codecov Report

Merging #7869 (720f948) into master (20f37b8) will decrease coverage by 0%.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #7869   +/-   ##
======================================
- Coverage      93%     92%   -0%     
======================================
  Files         202     202           
  Lines       13123   13123           
======================================
- Hits        12156   12118   -38     
- Misses        967    1005   +38     

[kaushikb11]

Did we create an issue on fsspec end?

[f4hy]

@awaelchli this requires all users of lighting to also get the latest version of fsspec. is there a feature we are using that is incompatible with older builds of fsspec?

[awaelchli]

it affects all lightning users? why?

If I remember correctly it had to do with tmpdir in pytest fixture not being a string and fsspec from one version to another had problems with that. A possible solution is #7876 maybe?