ci: push the database to Docker Hub

[knqyf263]

Close #441

[knqyf263]

I confirmed it could successfully publish the DB to Docker Hub.
https://github.com/aquasecurity/trivy-db/actions/runs/11288139164/job/31395337178

It's available here.

Also, it works with Trivy.

$ trivy image --db-repository aquasec/trivy-db:2 alpine:3.20
2024-10-11T11:45:06+04:00       INFO    [vulndb] Need to update DB
2024-10-11T11:45:06+04:00       INFO    [vulndb] Downloading vulnerability DB...
2024-10-11T11:45:06+04:00       INFO    [vulndb] Downloading artifact...        repo="aquasec/trivy-db:2"
54.15 MiB / 54.15 MiB [---------------------------------------------------------------------------------------------------------------] 100.00% 15.72 MiB p/s 3.6s
2024-10-11T11:45:13+04:00       INFO    [vulndb] Artifact successfully downloaded       repo="aquasec/trivy-db:2"

[DmitriyLewen]

LGTM