Currently just runs the ingest workflow and uploads the results
to AWS S3. Subsequent commits will add automation for the phylogenetic
workflow.

Follows Zika PR #52

nextstrain/zika@d44f2ae

The phylogenetic workflow will run after the ingest workflow has
completed successfully to use the latest available data.

Subsequent commits will check if the ingest results included new
data to only run the phylogenetic workflow when there's new data.

Following Zika PR #52

nextstrain/zika@2c415e7

Uses GitHub Actions cache to store a file that contains the
`Metadata.sh256sum` of the ingest files on S3 and use
the `hashFiles` function to create a unique cache key.

Then the existence of the cache key is an indicator that the ingest
file contents have not been updated since a previous run on GH Actions.
This does come with a big caveat that GH will remove any cache entries
that have not been accessed in over 7 days.¹ If the workflow is not
being automatically run within 7 days, then it will always run the
phylogenetic job.

If this works well, then we may want to consider moving this within
the `pathogen-repo-build` reusable workflow to have the same
functionality across pathogen automation workflows.

¹ https://docs.github.com/en/actions/using-workflows/caching-dependencies-to-speed-up-workflows#usage-limits-and-eviction-policy

Follows Zika PR #52

nextstrain/zika@eb5e76d

Add individuals inputs per workflow to override the default Docker image
used by `nextstrain build`. Having this input has been extremely helpful
to continue running pathogen workflows when we run into new bugs that
are not present in older nextstrain-base images.

There are separate image inputs for the two workflows because they use
different tools and may require different versions of images.

Follows Zika PR #52

nextstrain/zika@65a8acc

Copied daily schedule of mpox ingest
https://github.com/nextstrain/mpox/blob/e439235ff1c1d66e7285b774e9536e2896d9cd2f/.github/workflows/fetch-and-ingest.yaml#L4-L21

Daily runs seem fine since the ingest workflow currently takes less
than 2 minutes to complete and it will not trigger the phylogenetic
workflow if there's no new data.

We can bring this down to once a week if it seems like overkill.

Follows Zika PR #52

nextstrain/zika@77ca1d4

Follows Zika PR #52
nextstrain/zika@cdd071e

Follows Zika PR #52
nextstrain/zika@f615170

Uses the variable `AWS_DEFAULT_REGION` that was added to the
Nextstrain GitHub organization variables.¹

¹ https://github.com/organizations/nextstrain/settings/variables/actions