fix: add async for createPeerConnection when use await call it

[grootgordon]

Description When use VSCode edit main.js, if we call await createPeerConnection();

there is a warning of: 'await' has no effect on the type of this expression.ts(80007 Purpose resolve warning

[google-cla[bot]]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[grootgordon]

sign CLA done.