Theme: Update precomputed color ramps script for Node.js v20.10 compatibility (#72971)

Co-authored-by: aduth <aduth@git.wordpress.org>
Co-authored-by: jsnajdr <jsnajdr@git.wordpress.org>
Co-authored-by: hbhalodia <hbhalodia@git.wordpress.org>

Author: 3 people

packages/theme/bin/generate-default-ramps/index.ts

@@ -2,7 +2,8 @@
  * External dependencies
  */
 import { writeFile } from 'node:fs/promises';
-import { join } from 'node:path';
+import { dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
 
 /**
  * Internal dependencies
@@ -13,6 +14,8 @@ import {
 	buildAccentRamp,
 } from '../../src/color-ramps/index.ts';
 
+const __dirname = dirname( fileURLToPath( import.meta.url ) );
+
 const bgRamp = buildBgRamp( DEFAULT_SEED_COLORS.bg );
 const accentRamps = Object.fromEntries(
 	[ ...Object.entries( DEFAULT_SEED_COLORS ) ]
@@ -26,7 +29,7 @@ const accentRamps = Object.fromEntries(
 const ramps = { bg: bgRamp, ...accentRamps };
 
 const outputPath = join(
-	import.meta.dirname,
+	__dirname,
 	'../../src/color-ramps/lib/default-ramps.ts'
 );