update github actions to commits

Author: rxbchen

.github/dependabot.yaml

@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: "/"
+    schedule:
+      interval: weekly

.github/workflows/ci.yml

@@ -12,8 +12,8 @@ jobs:
           - { ruby: ruby-head, allowed-failure: true }
     name: Test Ruby ${{ matrix.entry.ruby }}
     steps:
-      - uses: actions/checkout@v3
-      - uses: ruby/setup-ruby@v1
+      - uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744 # v3.6.0
+      - uses: ruby/setup-ruby@dffc446db9ba5a0c4446edb5bca1c5c473a806c5 # v1.235.0
         with:
           ruby-version: ${{ matrix.entry.ruby }}
           bundler-cache: true