Update the hasher to call getRepoStateAsync instead of getPackageDeps

[jcreamer898]

There is a new way to calculate the hashes of the repo in rushstack.

Previously we used...

import { getPackageDeps } from "@rushstack/package-deps-hash";

https://github.com/microsoft/backfill/blob/main/packages/hasher/src/repoInfo.ts#L9

But, the Rush team has added similar functionality in https://github.com/microsoft/rushstack/blob/main/libraries/package-deps-hash/src/getRepoState.ts#L384

The getPackageDeps calls ls-tree which is slow under certain circumstances. (microsoft/rushstack#5499)

The new functionality uses ls-files which alleviates the issue.