ci(release-drafter): disable automatic triggers (#2181)

The action fails on every push and PR event because the repo has no
releases, triggering a known pagination bug in release-drafter@v7
("Data doesn't contain nodes field"). Since no releases are planned,
replace all automatic triggers with workflow_dispatch so it can still
be invoked manually if ever needed.

Signed-off-by: Bruno Verachten <gounthar@gmail.com>

Author: gounthar

.github/workflows/release-drafter.yml

@@ -1,17 +1,7 @@
 name: Release Drafter
 
 on:
-  push:
-    # branches to consider in the event; optional, defaults to all
-    branches:
-      - main
-  # pull_request event is required only for autolabeler
-  pull_request:
-    # Only following types are handled by the action, but one can default to all as well
-    types: [opened, reopened, synchronize]
-  # pull_request_target event is required for autolabeler to support PRs from forks
-  # pull_request_target:
-  #   types: [opened, reopened, synchronize]
+  workflow_dispatch:
 
 permissions:
   contents: read
@@ -35,4 +25,4 @@ jobs:
         #   config-name: my-config.yml
         #   disable-autolabeler: true
         env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}