README: Update badges

One of the badges was not working. That's a good opportunity to update them.
Now badges reflect status of master - not latest release - because that
better reflects the state of repository. I also added a badge for
integration tests.

Author: Lorak-mmk

README.rst

@@ -4,11 +4,14 @@ Scylla Python Driver
 A modern, feature-rich and highly-tunable Python client library for Scylla Open Source (2.1+) and Apache Cassandra (2.1+) and
 Scylla Enterprise (2018.1.x+) using exclusively Cassandra's binary protocol and Cassandra Query Language v3.
 
-.. image:: https://github.com/scylladb/python-driver/workflows/Build%20and%20upload%20to%20PyPi/badge.svg?tag=*-scylla
-   :target: https://github.com/scylladb/python-driver/actions?query=workflow%3A%22Build+and+upload+to+PyPi%22+event%3Apush+branch%3A*-scylla
+.. image:: https://github.com/scylladb/python-driver/actions/workflows/build-push.yml/badge.svg?branch=master
+   :target: https://github.com/scylladb/python-driver/actions/workflows/build-push.yml?query=event%3Apush+branch%3Amaster
 
-.. image:: https://github.com/scylladb/python-driver/workflows/CI%20Docs/badge.svg?tag=*-scylla
-   :target: https://github.com/scylladb/python-driver/actions?query=workflow%3A%22CI+Docs%22+event%3Apush+branch%3A*-scylla
+.. image:: https://github.com/scylladb/python-driver/actions/workflows/docs-pages.yaml/badge.svg?branch=master
+   :target: https://github.com/scylladb/python-driver/actions/workflows/docs-pages.yaml?query=event%3Apush+branch%3Amaster
+
+.. image:: https://github.com/scylladb/python-driver/actions/workflows/integration-tests.yml/badge.svg?branch=master
+   :target: https://github.com/scylladb/python-driver/actions/workflows/integration-tests.yml?query=event%3Apush+branch%3Amaster
 
 The driver supports Python versions 3.6-3.11.