fix: include src for sourcemaps (#817)

Author: Justin Poehnelt

package.json

@@ -33,7 +33,8 @@
   ],
   "main": "./dist/index.js",
   "files": [
-    "dist"
+    "dist",
+    "src"
   ],
   "scripts": {
     "docs": "rm -rf docs/ && typedoc src/index.ts",