cli-auth-config: explicitly message about skipped update

At the end of a auth-config command run, we ask the user if the newly
obtained token should be written on disk or discarded.

The default is to discard it (which seems a bit weird, but is not the
point here). Unlike what we do on write, where a green confirmation
message is displayed, we do not display any message when discarding.
So a user doing things a bit too fast can imagine that the update went
all fine as it just display a wall of green messages.

So we add a simple yellow message pointing out that we ultimately did
not write the new token. That should fix the problem.

swh/auth/cli.py

@@ -275,7 +275,10 @@ def auth_config(ctx: Context, username: str, token: str):
         ctx.fail(keycloak_error_message(ke))
 
     # Save auth configuration file?
+
+    msg = f"Skipping write of authentication configuration file {config_file}"
     if not click.confirm(f"Save authentication settings to {config_file}?"):
+        click.echo(click.style(msg, fg="yellow"))
         ctx.exit(0)
 
     # Save configuration to file