Pin TS version to 3.5.1

[HarshaNalluru]

Description

Brief description of the changes made in the PR. This helps in making better changelog

• Pin TS version to 3.5.1 to keep the dist artifacts look similar to the older ones.
• Artifacts with TS@3.9.x failed with bundling when tested with the package @azure/core-amqp that depends on rhea-promise https://dev.azure.com/azure-sdk/internal/_build/results?buildId=720614&view=logs&j=d25e7329-9524-595e-1030-bc1e9a340f40&t=0db4e429-9b55-5e39-a2c0-293aad8014c9