[Bug] input file in tools/Resources/README.md

https://github.com/Azure/autorest.powershell/blob/main/powershell/resources/assets/tools/Resources/README.md?plain=1#L74

Input file uri rely on commit from README.md. If developed from local environment, using local swagger. test-module.psd1 fail because no commit in README.md.

proposal:

- pin main branch in this file
- pin a commit id from main branch in this file
- save input file in assets