feat(pnpm): extract pnpm from engines for updating

lib/manager/npm/extract/__snapshots__/index.spec.ts.snap

@@ -33,6 +33,7 @@ Object {
   "compatibility": Object {
     "node": ">= 8.9.2",
     "npm": "^8.0.0",
+    "pnpm": "^1.2.0",
     "yarn": "disabled",
   },
   "deps": Array [
@@ -108,6 +109,14 @@ Object {
       "depType": "engines",
       "prettyDepType": "engine",
     },
+    Object {
+      "commitMessageTopic": "pnpm",
+      "currentValue": "^1.2.0",
+      "datasource": "npm",
+      "depName": "pnpm",
+      "depType": "engines",
+      "prettyDepType": "engine",
+    },
     Object {
       "commitMessageTopic": "Yarn",
       "currentValue": "disabled",

lib/manager/npm/extract/index.spec.ts

@@ -213,6 +213,7 @@ describe('manager/npm/extract', () => {
           atom: '>=1.7.0 <2.0.0',
           node: '>= 8.9.2',
           npm: '^8.0.0',
+          pnpm: '^1.2.0',
           yarn: 'disabled',
         },
         main: 'index.js',

lib/manager/npm/extract/index.ts

@@ -179,6 +179,10 @@ export async function extractPackageFile(
         dep.datasource = datasourceNpm.id;
         dep.commitMessageTopic = 'npm';
         compatibility.npm = dep.currentValue;
+      } else if (depName === 'pnpm') {
+        dep.datasource = datasourceNpm.id;
+        dep.commitMessageTopic = 'pnpm';
+        compatibility.pnpm = dep.currentValue;
       } else {
         dep.skipReason = SkipReason.UnknownEngines;
       }