fix: Add esm support to package.json (#211)

BREAKING CHANGE: changing to ESM may require changes by consumers of this library

Author: patrickedqvist

jest.config.js renamed to jest.config.mjs

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-module.exports = {
+export default {
   transform: {
     "^.+\\.tsx?$": "ts-jest",
   },