chore(issue_templates): Move niv update to operator-templating issue template (#726)

See: stackabletech/operator-templating#511

Author: NickLarsenNZ

.github/ISSUE_TEMPLATE/06-release.md

@@ -33,7 +33,6 @@ assignees: ''
 - [ ] Define product versions to include in the next release
 - [ ] [Major or Minor Container Images updates][epr-2]
 - [ ] [Patch Container Images updates][epr-2] (Do not reuse the previous issue)
-- [ ] Run `niv update` and test via `make run-dev` (operator-templating)
 
 [epr-1]: https://github.com/stackabletech/issues/issues/new?template=08-release-retro.md
 [epr-2]: https://github.com/stackabletech/docker-images/issues/new?template=early-pre-release.md