fix: use __require fallback for __dirname to support Node < 20.11.0

`import.meta.dirname` is unavailable before Node 20.11.0. The previous
fallback was dropped because `path`/`fileURLToPath` weren't in scope at
that point in the bun-generated __commonJS IIFE. Using `__require` (a
module-level closure bun always emits) works at any Node version.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: mdesmet

packages/dbt-tools/script/copy-python.ts

@@ -24,7 +24,7 @@ const pattern = /var __dirname\s*=\s*"[^"]*python-bridge[^"]*"/
 if (pattern.test(code)) {
   // import.meta.dirname is supported by Bun and Node >= 20.11.0.
   // Node 18 is EOL (April 2025), so no fallback needed.
-  const replacement = `var __dirname = import.meta.dirname`
+  const replacement = `var __dirname = typeof import.meta.dirname === "string" ? import.meta.dirname : __require("path").dirname(__require("url").fileURLToPath(import.meta.url))`
   code = code.replace(pattern, replacement)
   writeFileSync(indexPath, code)
   console.log(`Patched __dirname in dist/index.js`)