ci: pin GitHub Actions with pinact

Author: ryoppippi

.github/workflows/dependabot-auto-merge.yaml

@@ -18,12 +18,12 @@ jobs:
     steps:
       - name: Fetch Dependabot metadata
         id: metadata
-        uses: dependabot/fetch-metadata@v2
+        uses: dependabot/fetch-metadata@08eff52bf64351f401fb50d4972fa95b9f2c2d1b # v2.4.0
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Wait for CI to pass
-        uses: lewagon/[email protected]
+        uses: lewagon/wait-on-check-action@ccfb013c15c8afb7bf2b7c028fb74dc5a068cccc # v1.3.4
         with:
           ref: ${{ github.event.pull_request.head.sha }}
           running-workflow-name: Dependabot auto-merge

.github/workflows/nix-flake-update.yaml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
 
       - name: Setup Nix
         uses: ./.github/actions/setup-nix
@@ -35,7 +35,7 @@ jobs:
       - name: Create Pull Request
         id: create-pr
         if: steps.check-changes.outputs.changed == 'true'
-        uses: peter-evans/create-pull-request@v7
+        uses: peter-evans/create-pull-request@22a9089034f40e5a961c8808d113e2c98fb63676 # v7.0.11
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           commit-message: 'chore(deps): update nix flake inputs'