Python: pin minimum 'google-api-core[grpc]' dep to '1.4.1'.

[tseaver]

Closees #2404.

[codecov-io]

Codecov Report

Merging #2405 into master will not change coverage.
The diff coverage is 100%.

@@            Coverage Diff            @@
##             master    #2405   +/-   ##
=========================================
  Coverage     86.72%   86.72%           
  Complexity     5241     5241           
=========================================
  Files           458      458           
  Lines         20867    20867           
  Branches       2252     2252           
=========================================
  Hits          18096    18096           
  Misses         1968     1968           
  Partials        803      803

Impacted Files	Coverage Δ	Complexity Δ
...ansformer/py/PythonPackageMetadataTransformer.java	97.89% <100%> (ø)	36 <0> (ø)	⬇️

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