use payload from dispatches

[sbidari]

No description provided.

[O957]

Originally, I had

...so that users do not manually have to enter the reference date again when https://github.com/CDCgov/covidhub-reports/blob/main/.github/workflows/generate-visualization-data.yaml is ran.

in CDCgov/covid19-forecast-hub#1163 but I am not sure whether it is best to keep manual entry an option. Right now I have ${{ inputs.reference_date || github.event.client_payload.reference_date }} instead of ${{ github.event.client_payload.reference_date }}

[O957]

Waiting for remark from @sbidari on my own comment. get_hub_repo makes sense but maybe there is marginally better name?

[sbidari]

payload does not contain reference_date, it should just be ${{ inputs.reference_date }}