style: configure deno fmt to use single quotes

- Add singleQuote: true to deno.json fmt configuration
- Reformat all files with single quotes using deno fmt

ts/index.ts

@@ -2,6 +2,7 @@
 
 import { NupstCli } from './cli.ts';
 import { logger } from './logger.ts';
+import process from 'node:process';
 
 /**
  * Main entry point for NUPST
@@ -13,7 +14,7 @@ async function main() {
 }
 
 // Run the main function and handle any errors
-main().catch(error => {
+main().catch((error) => {
   logger.error(`Error: ${error}`);
   process.exit(1);
 });