fix: remove npx

package.json

@@ -8,7 +8,7 @@
   "scripts": {
     "test": "mocha -r ts-node/register tests/**/*.test.ts",
     "testWithCoverage": "nyc -r lcov -e .ts -x \"*.test.ts\" mocha -r ts-node/register tests/**/*.test.ts && nyc report",
-    "build": "npx tsc",
+    "build": "tsc",
     "format": "prettier --write \"src/**/*.ts\" \"src/**/*.js\" \"tests/**/*.ts\" \"tests/**/*.js\"",
     "lint": "tslint -p tsconfig.json",
     "install": "npm run build"