chore: update dependencies

[Goldziher]

This PR does the following:

1. update the go version and dependencies version in go.mod/go.sum.
2. update the versions of CI actions.
3. add dependabot config to ensure CI versions are updated.

[Goldziher]

@leg100 - thanks for this library. I want to use it, but its important to me that versions are updated. Especially anything that is cryptographically related. Hence this PR.

[leg100]

LGTM. Thanks!