ci: allow triggering npm release with workflow_dispatch

[pieh]

not tested, generated with copilot but it looks about right

hopefully it would allow to resolve https://linear.app/netlify/issue/FRB-1972/build-failures-due-to-dependency-issue-of-no-matching-version-found

see https://netlify.slack.com/archives/CTCRT6VB6/p1756261623711189 thread and in particular:

@netlify/blobs@10.0.9 is not on npm
> npm info @netlify/blobs@^10 version
@netlify/blobs@10.0.0 '10.0.0'
@netlify/blobs@10.0.1 '10.0.1'
@netlify/blobs@10.0.2 '10.0.2'
@netlify/blobs@10.0.3 '10.0.3'
@netlify/blobs@10.0.4 '10.0.4'
@netlify/blobs@10.0.5 '10.0.5'
@netlify/blobs@10.0.6 '10.0.6'
@netlify/blobs@10.0.7 '10.0.7'
@netlify/blobs@10.0.8 '10.0.8'
This https://github.com/netlify/primitives/actions/runs/17064432515/job/48378186948 should have released it to npm, but it failed.
Now since that there were other releases for other packages in this repo after above. Some of those packages depend on @netlify/blobs and because of release-please flows, blobs dependency in other packages (like @netlify/functions etc) was bumped to 10.0.9 , but it can't be resolved on installation due to it not being on npm in first place.
I tried rerunning that failed release please job, but it runs against main and not concrete commit, so it was no-op in the retry run (didn't attempt to publish anything), so I need to find other way to release those missing things to npm

[JakeChampion]

this if looks wrong - it will only run on a push event and not a workflow_dispatch

[pieh]

Retroactive reply copied from https://netlify.slack.com/archives/CTCRT6VB6/p1756284027411759?thread_ts=1756261623.711189&cid=CTCRT6VB6

Skipping the release please seemed fine, because release please action there only figures out packages to publish and I wanted to just attempt to publish everything as-is and ideally just ignore the cases of trying to publish version that is already on npm