@actions/exec: convert to ESM module

packages/exec/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@actions/exec",
-  "version": "2.0.0",
+  "version": "3.0.0",
   "description": "Actions exec lib",
   "keywords": [
     "github",
@@ -9,8 +9,15 @@
   ],
   "homepage": "https://github.com/actions/toolkit/tree/main/packages/exec",
   "license": "MIT",
+  "type": "module",
   "main": "lib/exec.js",
   "types": "lib/exec.d.ts",
+  "exports": {
+    ".": {
+      "types": "./lib/exec.d.ts",
+      "import": "./lib/exec.js"
+    }
+  },
   "directories": {
     "lib": "lib",
     "test": "__tests__"
@@ -36,6 +43,6 @@
     "url": "https://github.com/actions/toolkit/issues"
   },
   "dependencies": {
-    "@actions/io": "^2.0.0"
+    "@actions/io": "file:../io"
   }
 }