fix: field string values are correctly escaped in DataFrame serialization

[bednar]

Closes #153

Proposed Changes

• string fields are correctly serialized

Checklist

• CHANGELOG.md updated
• Rebased/mergeable
• A test has been added if appropriate
• pytest tests completes successfully
• Commit messages are in semantic format
• Sign CLA (if not already signed)

[codecov-commenter]

Codecov Report

Merging #154 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #154   +/-   ##
=======================================
  Coverage   89.15%   89.15%           
=======================================
  Files          25       25           
  Lines        1918     1918           
=======================================
  Hits         1710     1710           
  Misses        208      208           

Impacted Files	Coverage Δ
...fluxdb_client/client/write/dataframe_serializer.py	96.66% <100.00%> (ø)

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