Remove upper bound on importlib-resources (2.0 works)

[asottile]

this fixes a diamond incompatibility with pre-commit when installed on python<3.8

[codecov]

Codecov Report

Merging #1851 into master will increase coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1851      +/-   ##
==========================================
+ Coverage   88.72%   88.77%   +0.05%     
==========================================
  Files          82       82              
  Lines        3946     3946              
==========================================
+ Hits         3501     3503       +2     
+ Misses        445      443       -2     

Flag	Coverage Δ
#tests	88.77% <ø> (+0.05%)	⬆️

Impacted Files	Coverage Δ
...ualenv/create/via_global_ref/builtin/pypy/pypy2.py	98.70% <0.00%> (+2.59%)	⬆️

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