[python] specify autorest.python verification PR should be draft (#5515)

Co-authored-by: iscai-msft <[email protected]>

Author: iscai-msft

packages/http-client-python/CONTRIBUTING.md

@@ -12,7 +12,7 @@ To make the downstream PR, follow these steps:
    a. Click on the section that says `5 published; 1 consumed`, like in the above picture
    b. Follow `Published artifacts -> build_artifacts_python -> packages -> typespec-http-client-python-x.x.x.tgz`.
    c. Go to the right side, click the three dots, and click `Copy download url`.
-3. Create a PR in [autorest.python](https://github.com/Azure/autorest.python), updating the version of the `@typespec/http-client-python` in the `package.json` files to be the downloaded URL
+3. Create a _draft_ PR in [autorest.python](https://github.com/Azure/autorest.python), updating the version of the `@typespec/http-client-python` in the `package.json` files to be the downloaded URL
 4. Run `pnpm install`, and follow that repo's [CONTRIBUTING.md](https://github.com/Azure/autorest.python/blob/main/CONTRIBUTING.md) for your second PR
 5. Once the PR to [autorest.python](https://github.com/Azure/autorest.python) passes, you can merge and release the original PR
 6. When the change to `@typespec/http-client-python` has been released, update your [autorest.python](https://github.com/Azure/autorest.python) repo to use the released version of the `@typespec/http-client-python` package