start release pipeline on workflow_dispatch

[bruelea]

So far the image version and change log were only created after the release was published, so the tag in the release note didn't point to the commit in which the image version is bumped.

With the new manually triggered workflow the new version and a release summary can be used as parameters to create a new release where the tag points to the commit in which the image is bumped.
This PR is based on the proposal of @alexandernorth and @pablogarciamiranda.

Tested in this fork: https://github.com/bruelea/netbox-operator

Fixed netbox deployment in e2e tests by using bitnamilegacy image repository

[alexandernorth]

Was doing this from my phone apologies if I didn’t see some reference

[faebr]

The sample release in your fork looks good

[bruelea]

Thanks for the suggestions. I cleaned up some parts of the script based on the comments and tested it in the forked repo.

[alexandernorth]

LGTM