Add shell: true to TSP install command. (#3243)

This is a breakage due to a breaking change in node's latest incremental
version. (See nodejs/node#52554 for
background). Adding shell: true fixes this.

Fixes #3242.

---------

Co-authored-by: Timothee Guerin <timothee.guerin@outlook.com>

.chronus/changes/main-2024-3-26-15-49-18.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@typespec/compiler"
+---
+
+Fix calling `tsp install` on windows due to recent NodeJS breaking change to fix vulnerability.

packages/compiler/src/core/install.ts

@@ -13,8 +13,8 @@ export async function installTypeSpecDependencies(
   host: CliCompilerHost,
   directory: string
 ): Promise<void> {
-  const cmd = process.platform === "win32" ? "npm.cmd" : "npm";
-  const child = spawn(cmd, ["install"], {
+  const child = spawn("npm", ["install"], {
+    shell: process.platform === "win32",
     stdio: "inherit",
     cwd: directory,
     env: process.env,