Enable workflow_dispatch and scheduled builds for all CI runners.

.github/workflows/ci-alpine.yml

@@ -4,6 +4,7 @@ on:
   push:
   schedule:
     - cron: '0 0 * * 0'
+  workflow_dispatch:
 jobs:
   build:
     if: "!contains(github.event.head_commit.message, '[skip alpine ci]')"

.github/workflows/ci-linux.yml

@@ -1,7 +1,10 @@
 name: Ubuntu CI
 on:
-  - pull_request
-  - push
+  pull_request:
+  push:
+  schedule:
+    - cron: '0 0 * * 0'
+  workflow_dispatch:
 jobs:
   build:
     if: "!contains(github.event.head_commit.message, '[skip ubuntu ci]')"

.github/workflows/ci-windows.yml

@@ -7,6 +7,7 @@ on:
       - published
   schedule:
     - cron: '0 0 * * 0'
+  workflow_dispatch:
 jobs:
   build:
     if: "!contains(github.event.head_commit.message, '[skip windows ci]')"