Fix hydrogen upgrade failing with yarn and pnpm

The upgrade command was using `installNodeModules` which always runs
`<pm> install <packages>`. This works for npm but fails for yarn, pnpm,
and bun which require `add` instead of `install` when adding/upgrading
specific packages. Mirror the pattern already used by
`uninstallNodeModules` which correctly maps the subcommand per package
manager.

Author: Umar Gora

.changeset/fix-yarn-upgrade-command.md

@@ -0,0 +1,5 @@
+---
+'@shopify/cli-hydrogen': patch
+---
+
+Fix `hydrogen upgrade` failing with yarn by using `yarn add` instead of `yarn install` when upgrading dependencies

packages/cli/src/commands/hydrogen/upgrade.ts

@@ -23,7 +23,6 @@ import {
 } from '@shopify/cli-kit/node/fs';
 import {
   getDependencies,
-  installNodeModules,
   getPackageManager,
   type PackageJson,
 } from '@shopify/cli-kit/node/node-package-manager';
@@ -903,10 +902,13 @@ export async function upgradeNodeModules({
     tasks.push({
       title: `Upgrading dependencies`,
       task: async () => {
-        await installNodeModules({
-          directory: appPath,
-          packageManager: await getPackageManager(appPath),
-          args: upgradeArgs,
+        const packageManager = await getPackageManager(appPath);
+        const command = packageManager === 'npm' ? 'install' : 'add';
+        const actualPackageManager =
+          packageManager === 'unknown' ? 'npm' : packageManager;
+
+        await exec(actualPackageManager, [command, ...upgradeArgs], {
+          cwd: appPath,
         });
       },
     });