Resolves: Add security and versioning dependency alerts

[szlatkow]

• add dependabot.yml which automatically enables Dependabot's dependency versioning scanner and dependency update PRs bot by declaring dependency ecosystems and sources in the project. For dependency security vulnerabilities scanner and vulnerable dependency update PRs bot, enable "Dependabot alerts" and "Dependabot security updates"

Resolves #23

[ardalis]

Thanks!