Issue 978: Fix Custom cookie name breaks redis for session (#1949)

* Issue 978: Fix Custom cookie name breaks redis for session (see https://github.com/oauth2-proxy/oauth2-proxy/issues/978)

* Issue 978: Fix Custom cookie name breaks redis for session (see https://github.com/oauth2-proxy/oauth2-proxy/issues/978)

* Update CHANGELOG.md

* Issue 978: Fix Custom cookie name breaks redis for session

* Issue 978: Fix Custom cookie name breaks redis for session

* Issue 978: Fix Custom cookie name breaks redis for session

* Issue 978: Fix Custom cookie name breaks redis for session

* Issue 978: Fix Custom cookie name breaks redis for session

* Issue 978: Fix Custom cookie name breaks redis for session

* Update CHANGELOG.md

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Co-authored-by: Nuno Borges <Nuno.Borges@ctw.bmwgroup.com>
Co-authored-by: Joel Speed <Joel.speed@hotmail.co.uk>