Simplify CI triggers and add keepalive action

.github/workflows/ci.yml

@@ -2,20 +2,10 @@
 name: ci
 on:
   push:
-    paths:
-    - ".github/workflows/ci.yml"
-    - lib/**
-    - "*.gemspec"
-    - spec/**
-    - Rakefile
-    - Gemfile
-    - Gemfile.devtools
-    - ".rubocop.yml"
-    - project.yml
   pull_request:
-    branches:
-    - master
   create:
+  schedule:
+    - cron: "30 4 * * *"
 jobs:
   tests:
     runs-on: ubuntu-latest
@@ -86,3 +76,11 @@ jobs:
       run: |
         tag=$(echo $GITHUB_REF | cut -d / -f 3)
         ossy gh w rom-rb/devtools release --payload "{\"tag\":\"$tag\",\"sha\":\"${{github.sha}}\",\"tag_creator\":\"$GITHUB_ACTOR\",\"repo\":\"$GITHUB_REPOSITORY\",\"repo_name\":\"${{github.event.repository.name}}\"}"
+
+  workflow-keepalive:
+    if: github.event_name == 'schedule'
+    runs-on: ubuntu-latest
+    permissions:
+      actions: write
+    steps:
+      - uses: liskin/gh-workflow-keepalive@v1