Bump actions/checkout from 2 to 3 (#27)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 3.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v3)

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

Signed-off-by: dependabot[bot] <[email protected]>

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/compile-fw.yml

@@ -31,7 +31,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Compile
         uses: arduino/compile-sketches@main

.github/workflows/general-formatting-checks.yml

@@ -10,7 +10,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       # https://github.com/per1234/formatting-checks
       - name: Check for files starting with a blank line

.github/workflows/spell-check.yml

@@ -10,7 +10,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Spell check
         uses: codespell-project/actions-codespell@master

.github/workflows/sync-labels.yml

@@ -27,7 +27,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Download JSON schema for labels configuration file
         id: download-schema
@@ -99,7 +99,7 @@ jobs:
           echo "::set-output name=flag::--dry-run"
 
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Download configuration files artifact
         uses: actions/download-artifact@v2