DRIVERS-2915 OIDC: Add missing data in connection string test (mongodb#1602)

Author: blink1073

source/connection-string/tests/valid-warnings.json

@@ -84,4 +84,5 @@ tests:
                 host: "localhost"
                 port: ~
         auth: ~
-        options: ~
+        options:
+            authMechanism: MONGODB-OIDC