[keyserver] Fix stalling of keyserver public key script

Summary: Should've noticed this in D8448. We initialize the MySQL connection but never close it, which is why the script stalls. This is addressed by using the `main` util (all scripts are supposed to use this).

Test Plan: Run script locally, confirm it no longer stalls

Reviewers: varun

Reviewed By: varun

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D8449

keyserver/src/scripts/get-keyserver-public-key.js

@@ -1,11 +1,12 @@
 // @flow
 
+import { main } from './utils.js';
 import { fetchOlmAccount } from '../updaters/olm-account-updater.js';
 
 // Outputs the keyserver's signing ed25519 public key
-async function main() {
+async function getKeyserverPublicKey() {
   const info = await fetchOlmAccount('content');
   console.log(JSON.parse(info.account.identity_keys()).ed25519);
 }
 
-main();
+main([getKeyserverPublicKey]);