Update README.md

Author: Dzmitry Humianiuk

README.md

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 # ReportPortal python client
 
-[![PyPI](https://img.shields.io/pypi/v/reportportal-client.svg?maxAge=2592000)](https://pypi.python.org/pypi/reportportal-client)
+[![PyPI](https://img.shields.io/pypi/v/reportportal-client.svg?maxAge=259200)](https://pypi.python.org/pypi/reportportal-client)
 [![Build Status](https://travis-ci.org/reportportal/client-Python.svg?branch=master)](https://travis-ci.org/reportportal/client-Python)
 
 Library used only for implementors of custom listeners for ReportPortal