chore: add types to exports field (#178)

Author: awlayton

package.json

@@ -7,6 +7,7 @@
   "exports": {
     "./package.json": "./package.json",
     ".": {
+      "types": "./src/jsonpath.d.ts",
       "browser": "./dist/index-browser-esm.js",
       "umd": "./dist/index-browser-umd.cjs",
       "import": "./dist/index-node-esm.js",