Added cross-env

Author: mattpocock

package-lock.json

@@ -7,6 +7,7 @@
   "devDependencies": {
     "@types/node": "^18.6.5",
     "chokidar": "^3.5.3",
+    "cross-env": "^7.0.3",
     "cross-fetch": "^3.1.5",
     "ts-toolbelt": "^9.6.0",
     "typescript": "^4.8.2",
@@ -15,7 +16,7 @@
   "scripts": {
     "exercise": "node scripts/exercise.js",
     "e": "npm run exercise",
-    "solution": "SOLUTION=true node scripts/exercise.js",
+    "solution": "cross-env SOLUTION=true node scripts/exercise.js",
     "s": "npm run solution",
     "prepare": "node ./scripts/prepare-stackblitz.js",
     "e-01": "npm run exercise -- 01",
@@ -119,4 +120,4 @@
     "fast-glob": "^3.2.12",
     "zod": "^3.17.10"
   }
-}
+}