Add TuxCare ecosystem support

[Korulag]

• Prepare your data - refer to the OSV Schema documentation for information on how to properly format the data so it can be accepted.
  Our OSV data source is https://github.com/cloudlinux/tuxcare-osv.

• Create a PR to reserve an ID prefix and define a new ecosystem (example). We review the records you start publishing for OSV Schema correctness and quality as part of reviewing and merging this PR.
  Add TuxCare ecosystem ossf/osv-schema#520

• Prepare and publish your records via a Git repository (example). If this method isn’t ideal, we also support publishing records from REST API endpoints or through a GCS bucket(example).

• To support API querying, please create a PR to extend purl_helpers.py and create a new ecosystem in _ecosystems.py. You can refer to existing examples showing how to implement support for Semver and non-Semver ecosystems.

• Create a PR to start importing the records you are publishing into our test instance of OSV.dev and validate everything is working as intended there.
  feat: Add test ingestion of advisories for Tuxcare ecosystem #4968

• Create a PR to start importing the records you are publishing into our production environment

[michaelkedar]

Hi, I made #5231 as a placeholder to allow Tuxcare to be ingested into OSV.dev, but without an implementation, we won't be able to match it on the API.
What versioning rules do Tuxcare packages use? From a quick glance it seems to me to be based on RPM?

[michaelkedar]

Actually, I've noticed that your records use Tuxcare as the ecosystem, while in the schema it is TuxCare

The ecosystem field is case sensitive - could you please update the records?