rhysd/actionlint v1.6.4 on GitHub

Implement 'map' object types { string => T }, where all properties of the object are typed as T. Since a key of object is always string, left hand side of => is fixed to string. For example, env context only has string properties so it is typed as { string => string}. Previously its properties were typed any.
```
# typed as string (previously any)
env.FOO

# typed as { id: string; network: string; ports: object; } (previously any)
job.services.redis
```
github.event.discussion.title and github.event.discussion.body are now checked as untrusted inputs.
Update popular actions data set. (#50, #51)
Update webhooks payload data set. branch_protection_rule hook was dropped from the list due to github/docs@179a6d3. (#50, #51)