Make "version" Keycloak provider's key null by default

Hello there!

A minor fix for the newly added Keycloak provider's version key to make it actually optional - it's set to null by default :)

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v2.13.1

Feb 3nd, 2023

What's Changed

• Set Keycloak provider's 'version' config option to null by default by @bocharsky-bw in #393

Full Changelog: v2.13.0...v2.13.1