refactor: use HTTResponse.headers instead deprecated HTTPResponse.getheaders()

[bednar]

Proposed Changes

Refactor code to not deprecated variant:

The deprecation warning also causes failure of CI build:

https://app.circleci.com/pipelines/github/influxdata/influxdb-client-python/2199/workflows/e1db935d-5dfd-4944-9beb-d113c4108e8b/jobs/12253

Checklist

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

[codecov-commenter]

Codecov Report

Base: 90.28% // Head: 90.28% // No change to project coverage 👍

Coverage data is based on head (9576138) compared to base (fc6f2d9).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #534   +/-   ##
=======================================
  Coverage   90.28%   90.28%           
=======================================
  Files          39       39           
  Lines        3428     3428           
=======================================
  Hits         3095     3095           
  Misses        333      333           

Impacted Files	Coverage Δ
influxdb_client/_sync/rest.py	86.99% <100.00%> (ø)

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[vlastahajek]

LGTM 👍

[melvilun]

Hi,

The deprecated method is still used in the getheader() method, which is defined below the getheaders() that you changed.

If you want to clear the deprecation warning for all cases, you need to update that method too.