Bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/arduino-lint.yaml

@@ -4,7 +4,7 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: arduino/arduino-lint-action@v2
         with:
           library-manager: update

.github/workflows/compile-arduino_wifinina-examples.yaml

@@ -45,7 +45,7 @@ jobs:
               - name: WiFiNINA
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Compile examples
         uses: arduino/compile-sketches@v1

.github/workflows/compile-seeed-studio-examples.yaml

@@ -56,7 +56,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Compile examples
         uses: arduino/compile-sketches@v1

.github/workflows/compile-unor4wifi-examples.yaml

@@ -37,7 +37,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Compile examples
         uses: arduino/compile-sketches@v1

.github/workflows/main.yml

@@ -17,7 +17,7 @@ jobs:
   check_version_files:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: check version
         run: |
@@ -26,7 +26,7 @@ jobs:
   prepare_example_json:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: generate examples
         id: set-matrix
@@ -61,7 +61,7 @@ jobs:
       ARDUINO_DIRECTORIES_DATA: /home/runner/arduino_ide
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Get hash
         id: get-hash
@@ -116,7 +116,7 @@ jobs:
 
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: install libgtk2.0-0
         run: |