feat: add prebuild script to clean dist directory before build

Author: Odrin

package.json

@@ -3,6 +3,7 @@
   "version": "2.4.0-beta.1",
   "repository": "https://github.com/broxus/everscale-standalone-client",
   "scripts": {
+    "prebuild": "rm -rf dist",
     "build": "npm run build:cjs && npm run build:esm",
     "build:cjs": "tsc --module CommonJS --outDir dist/cjs --declaration false",
     "build:esm": "tsc --module ESNext --outDir dist/esm --declaration --declarationDir dist/esm",