Use a version (v1) instead of a 'deprecated' branch name

[ggrossetie]

The GitHub Action peter-evans/repository-dispatch has renamed the default branch from master to main.

We have the following warnings when the action is running:

peter-evans/repository-dispatch@master
Warning: This action's default branch has been renamed to "main"
Warning: Referencing this action with "@master" is deprecated and will stop working after June 30th 2021

https://github.com/neo4j-documentation/knowledge-base/runs/3749795275?check_suite_focus=true

Despite the warning message, the action is still running fine but to avoid issues it's better to use a tag name v1 instead of a branch name master.