Update README to use actions/checkout@v5

Author: kylewlacy

README.md

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Setup Brioche
         uses: brioche-dev/setup-brioche@v1
@@ -60,7 +60,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Setup Brioche
         uses: brioche-dev/setup-brioche@v1