splice-validator: make sure users (which are OIDC sub values) are quo…

[SLoeuillet]

…ted because Okta uses emails and '@' breaks yaml file loading if not quoted

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[giner]

Nice. Thank you!

[moritzkiefer-da]

thanks! Please include [static] in your commit message to trigger CI. no longer necessary

[moritzkiefer-da]

you're also missing the git signoff message

[moritzkiefer-da]

@SLoeuillet ping, you still need to fix the signoff for us to be able to merge this.