feat: Checks the health of a running InfluxDB instance by querying the /health

[bednar]

• CHANGELOG.md updated
• Rebased/mergeable
• Tests pass
• Sign CLA (if not already signed)

[codecov-io]

Codecov Report

Merging #14 into master will increase coverage by 5.05%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master      #14      +/-   ##
============================================
+ Coverage     79.96%   85.02%   +5.05%     
- Complexity      262      268       +6     
============================================
  Files            13       14       +1     
  Lines           584      601      +17     
============================================
+ Hits            467      511      +44     
+ Misses          117       90      -27     

Impacted Files	Coverage Δ	Complexity Δ
src/InfluxDB2/Client.php	100.00% <100.00%> (ø)	6.00 <1.00> (+1.00)
src/InfluxDB2/DefaultApi.php	80.85% <100.00%> (+2.27%)	14.00 <9.00> (+2.00)
src/InfluxDB2/HealthApi.php	100.00% <100.00%> (ø)	3.00 <3.00> (?)
src/InfluxDB2/ObjectSerializer.php	40.49% <0.00%> (+22.31%)	61.00% <0.00%> (ø%)

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