Update actions/checkout action to v6

Generated by renovateBot

Author: renovate[bot]

.github/workflows/browser-e2e.yaml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: test
         run: |
           docker build -t pion-webrtc-e2e -f e2e/Dockerfile .

.github/workflows/examples-tests.yaml

@@ -15,6 +15,6 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: test
         run: cd examples/pion-to-pion && ./test.sh

.github/workflows/standardjs.yaml

@@ -11,7 +11,7 @@ jobs:
   StandardJS:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-node@v5
         with:
           node-version: 24.x