Update the Keycloak contacts

[abstractj]

@arthurscchan @AdamKorcz @jonathanmetzman we created a dedicated mailing list for oss-fuzz and I would like us to change it. The change aims to have a focused communication channel for build failures and potential alerts about it. Could you please review?

//cc @stianst

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[github-actions]

abstractj is a new contributor to projects/keycloak. The PR must be approved by known contributors before it can be merged. The past contributors are: arthurscchan

[AdamKorcz]

@abstractj Could you sign the CLA?

[abstractj]

Thank you @AdamKorcz, signed the CLA. Hopefully it is all set now.

[github-actions]

abstractj is a new contributor to projects/keycloak. The PR must be approved by known contributors before it can be merged. The past contributors are: arthurscchan

[AdamKorcz]

@abstractj The CLA seems to not be signed yet for this email: b***o​@abstractj.com

[abstractj]

@AdamKorcz thank you, I hadn't realized that I had to trigger those checks again. Now, it should be ready.