ci: bump actions/checkout from 3 to 4

.github/workflows/build_documentation.yaml

@@ -22,7 +22,7 @@ jobs:
 
     steps:
       # check out the Arduino-SDI-12 repo
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           path: code_docs/Arduino-SDI-12
 
@@ -90,7 +90,7 @@ jobs:
 
       # check out my fork of m.css, for processing Doxygen output
       - name: Checkout m.css
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           # Repository name with owner. For example, actions/checkout
           repository: SRGDamia1/m.css

.github/workflows/build_examples.yaml

@@ -26,7 +26,7 @@ jobs:
           ]
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Set variables
         run: |

.github/workflows/changelog_reminder.yaml

@@ -5,7 +5,7 @@ jobs:
     name: Changelog Reminder
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           persist-credentials: false # otherwise, the token used is the GITHUB_TOKEN, instead of your personal token
 

.github/workflows/prepare_release.yaml

@@ -19,7 +19,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Set variables
         run: |

.github/workflows/verify_library_json.yaml

@@ -9,7 +9,7 @@ jobs:
     if: "!contains(github.event.head_commit.message, 'ci skip')"
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Setup Node.js
         uses: actions/setup-node@v3.6.0