chore: remove pytz library

[bednar]

Closes #447

Proposed Changes

1. Remove pytz library which is not necessary dependency.

Checklist

• CHANGELOG.md updated
• Rebased/mergeable
• pytest tests completes successfully
• Commit messages are conventional
• Sign CLA (if not already signed)

[codecov-commenter]

Codecov Report

Merging #449 (c6c364b) into master (2db3afc) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #449      +/-   ##
==========================================
- Coverage   89.35%   89.34%   -0.01%     
==========================================
  Files          38       38              
  Lines        3259     3258       -1     
==========================================
- Hits         2912     2911       -1     
  Misses        347      347              

Impacted Files	Coverage Δ
influxdb_client/client/util/date_utils.py	96.29% <100.00%> (ø)
influxdb_client/client/write/point.py	96.68% <100.00%> (-0.03%)	⬇️

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