refactor: use HTTResponse.headers instead deprecated HTTPResponse.getheader() (#601)

Author: londondaintta

CHANGELOG.md

@@ -1,5 +1,8 @@
 ## 1.38.0 [unreleased]
 
+### Bug Fixes
+1. [#601](https://github.com/influxdata/influxdb-client-python/pull/601): Use HTTResponse.headers to clear deprecation warning [urllib3]
+
 ### Documentation
 1. [#566](https://github.com/influxdata/influxdb-client-python/pull/566): Fix Sphinx documentation build and add support `.readthedocs.yml` V2 configuration file
 

influxdb_client/_sync/rest.py

@@ -47,7 +47,7 @@ def getheaders(self):
 
     def getheader(self, name, default=None):
         """Return a given response header."""
-        return self.urllib3_response.getheader(name, default)
+        return self.urllib3_response.headers.get(name, default)
 
 
 class RESTClientObject(object):