Fix creation_time calculation which was failing to auth with GH

[kendalharland]

Description

Before generating bigquery data we fetch the release's creation time with the gh CLI. This step has been silently failing with an auth error, resulting in the creation time being set to the current timestamp when data is sent to BQ.

Changes

• Set-StrictMode in the pwsh script to fail fast if future errors like this occur
• Throw in the python script if the creation time is empty (Should never happen, but just to be safe)
• Pin a toolchain version for testing.
• Add a pull_request trigger so this workflow can be tested.
• Add a dry_run input so we can skip uploading data during testing.

[kendalharland]

Forgot to make sure we pin a toolchain version for testing. Fixed in the latest patch

[kendalharland]

I was overconfident in my Powershell-fu and sent this for review too soon. Will fixup and resend