fix: project.yml should use functions over actions syntax

[KylePeterDavies]

The project.yml uses the old actions keyword over the newer functions keyword. While this is mentioned in the documentation it would be better to provide up to date samples with the newer specification. Also the sample project generated with doctl serverless init --language go name will use functions over actions.

[KylePeterDavies]

If you're happy with the changes I'l update the other samples. I'l do this after merge.