Set PYARROW_IGNORE_TIMEZONE for binder.

[ueshin]

We should set PYARROW_IGNORE_TIMEZONE environment variable for binder; otherwise it shows a warning:

[itholic]

LGTM. pending tests

[codecov-io]

Codecov Report

Merging #1965 (fc8ef7a) into master (eefe9b5) will decrease coverage by 0.88%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1965      +/-   ##
==========================================
- Coverage   94.60%   93.71%   -0.89%     
==========================================
  Files          49       49              
  Lines       10890    10890              
==========================================
- Hits        10302    10206      -96     
- Misses        588      684      +96     

Impacted Files	Coverage Δ
databricks/koalas/usage_logging/__init__.py	24.78% <0.00%> (-67.53%)	⬇️
databricks/koalas/usage_logging/usage_logger.py	47.82% <0.00%> (-52.18%)	⬇️
databricks/koalas/__init__.py	85.93% <0.00%> (-4.69%)	⬇️
databricks/conftest.py	97.10% <0.00%> (-2.90%)	⬇️

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