Update actions/checkout action to v6

Author: renovate-bot

.github/workflows/main.yml

@@ -17,7 +17,7 @@ jobs:
       - run: echo $env:BUILD_TOOLS_PATH | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
         if: startsWith(matrix.os, 'windows')
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Cache conan
         uses: actions/cache@v4

.github/workflows/sonarcloud.yml

@@ -13,7 +13,7 @@ jobs:
     env:
       CONAN_SYSREQUIRES_MODE: "enabled"
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0