Add pnpm package manager support

fixtures/pnpm/dev_deps/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "node_app_with_dev_deps_pnpm",
+  "version": "1.0.0",
+  "main": "server.js",
+  "author": "CF Buildpacks Team",
+  "description": "Node.js app with pnpm and dev dependencies",
+  "dependencies": {
+    "express": "^4.18.2"
+  },
+  "devDependencies": {
+    "jest": "^29.0.0",
+    "nodemon": "^2.0.20"
+  },
+  "engines": {
+    "pnpm": "*"
+  }
+}

fixtures/pnpm/dev_deps/server.js

@@ -0,0 +1,12 @@
+var express = require('express');
+
+var app = express();
+
+app.get('/', function(req, res) {
+  res.send('Hello from dev_deps!');
+});
+
+var port = process.env.PORT || 3000;
+app.listen(port, function() {
+  console.log("Listening on " + port);
+});

fixtures/pnpm/simple/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "node_web_app_with_pnpm",
+  "version": "1.0.0",
+  "main": "server.js",
+  "author": "CF Buildpacks Team",
+  "description": "Simple Node.js app with pnpm",
+  "dependencies": {
+    "express": "^4.18.2",
+    "logfmt": "^1.1.2"
+  },
+  "engines": {
+    "pnpm": "*"
+  }
+}