refactor: use HTTResponse.headers instead deprecated HTTPResponse.getheaders() (#534)

Author: bednar

CHANGELOG.md

@@ -6,6 +6,7 @@
 ### Bug Fixes
 1. [#526](https://github.com/influxdata/influxdb-client-python/pull/526): Creating client instance from static configuration
 1. [#531](https://github.com/influxdata/influxdb-client-python/pull/531): HTTP request return type for Management API [async/await]
+1. [#534](https://github.com/influxdata/influxdb-client-python/pull/534): Use `HTTResponse.headers` to clear deprecation warning [urllib3]
 
 ### CI
 1. [#523](https://github.com/influxdata/influxdb-client-python/pull/523): Add Python 3.11 to CI builds

influxdb_client/_sync/rest.py

@@ -43,7 +43,7 @@ def __init__(self, resp):
 
     def getheaders(self):
         """Return a dictionary of the response headers."""
-        return self.urllib3_response.getheaders()
+        return self.urllib3_response.headers
 
     def getheader(self, name, default=None):
         """Return a given response header."""