ci(core): attach a .deb to the release

`apt install ./core_0.12.4_amd64.deb` puts core on PATH, records it in
the package database, and removes cleanly. Unzipping does none of that.

Inert until dAppCore/build#76 lands and v4 moves: an action ignores an
input it does not declare, so this is a no-op rather than a failure in
the meantime.

Co-Authored-By: Virgil <virgil@lethean.io>

Author: Snider

.github/workflows/core.yml

@@ -57,6 +57,12 @@ jobs:
           ldflags: -s -w -X dappco.re/go/cli/pkg/cli.AppVersion=${{ github.ref_name }}
           # An artifact on every run; a release only on a tag.
           package: true
+          # A zip is a download; a .deb is an install. The Linux job attaches
+          # one so `apt install ./core_<version>_amd64.deb` works, which puts
+          # core on PATH and takes it off again cleanly.
+          deb: true
+          deb-maintainer: "Lethean <dev@lethean.io>"
+          deb-description: "Core developer CLI — build, lint, QA and packaging for CoreGO"
 
       - name: Check the binary answers
         # No working-directory: BINARY_PATH is relative to