Grant admin for first user on SSO/OIDC registration path. (fixes #315)

Signed-off-by: Jason Volk <jason@zemos.net>

src/api/client/session/sso.rs

@@ -479,6 +479,7 @@ async fn register_user(
 			password: Some("*"),
 			origin: Some("sso"),
 			displayname: userinfo.name.as_deref(),
+			grant_first_user_admin: true,
 			..Default::default()
 		})
 		.await?;