Enable dependabot and the usual GitHub scanning & updating infra

[lenucksi]

Hi,

I keep getting notified about security issues in dependencies for this org by GitHub. In you case e.g. this one:

• https://github.com/InnerSourceCommons/gatherings/security/dependabot/10

As I do not have the required access to just enable the matching Dependabot/CodeQL/... settings I can't give you the way to fix this. So please just enable that yourselves under Settings -> Advanced Security and see through whatever PR falls out of it. Usually all no-brainers.