update woodpecker config tag filter notation

[MikiDi]

The old notation is not compatible with our current version of Woodpecker any more.

[madnificent]

I've just made a release on another project which uses the following syntax which seems what we have here now:

  when:
    event: tag
    tag: v*

Is this a current or a future problem that would apply to many other repositories?

[MikiDi]

You indeed won't notice any problem when releasing how we usually do. The pipeline will however also trigger for a tag like my-tag (without the leading v), which is exactly what this config is meant to prevent.
It is a current problem since we are running a Woodpecker version that no longer supports this old syntax. Indeed applies to many other repos.
You can see the related discussion here: https://chat.semte.ch/group/docker?msg=76w3SXompgPR6WmdP