Store local yarn versions as .cjs files (#8145)

This improves the experience of working with yarn
in workspaces that are marked as "type": "module"
in the package.json file.

This change has also been applied in yarn 2, see yarnpkg/berry#1354

Author: bgotink

CHANGELOG.md

@@ -12,6 +12,10 @@ Please add one entry in this file for each change in Yarn's behavior. Use the sa
 
   [#8142](https://github.com/yarnpkg/yarn/pull/8142) - [**Merceyz**](https://github.com/merceyz)
 
+- Generates local yarn verions as `.cjs` files when calling `yarn set version`
+
+  [#8145](https://github.com/yarnpkg/yarn/pull/8145) - [**bgotink**](https://github.com/bgotink)
+
 ## 1.22.1
 
 - Prevents `yarn-path` from exiting before its child exited

src/cli/commands/policies.js

@@ -155,7 +155,7 @@ const {run, setFlags, examples} = buildSubCommands('policies', {
 
     const bundle = await fetchBundle(config, bundleUrl);
 
-    const yarnPath = path.resolve(config.lockfileFolder, `.yarn/releases/yarn-${bundleVersion}.js`);
+    const yarnPath = path.resolve(config.lockfileFolder, `.yarn/releases/yarn-${bundleVersion}.cjs`);
     reporter.log(`Saving it into ${chalk.magenta(yarnPath)}...`);
     await fs.mkdirp(path.dirname(yarnPath));
     await fs.writeFile(yarnPath, bundle);