chore(deps): update actions/checkout digest to b4ffde6 (#140)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

.github/workflows/main.yml

@@ -40,7 +40,7 @@ jobs:
 
     steps:
       - name: $ git clone する
-        uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
       - name: Ruby をセットアップする
         uses: ruby/setup-ruby@v1
         with: