[deps]: Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/a11y-eval-browser.yml

@@ -23,7 +23,7 @@ jobs:
       packages: read
     steps:
       - name: Checkout
-        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
         with:
           persist-credentials: false
       - name: Setup Node

.github/workflows/a11y-eval-web.yml

@@ -19,7 +19,7 @@ jobs:
       packages: read
     steps:
       - name: Checkout
-        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
         with:
           persist-credentials: false
       - name: Setup Node

.github/workflows/test-all-custom-flags.yml

@@ -74,7 +74,7 @@ jobs:
           permission-issues: write
 
       - name: Checkout
-        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
         with:
           persist-credentials: false
       - name: Setup Node

.github/workflows/test-all.yml

@@ -74,7 +74,7 @@ jobs:
           permission-issues: write
 
       - name: Checkout
-        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
         with:
           persist-credentials: false