Bump actions/checkout from 2 to 5

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 5.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v5)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/main.yml

@@ -33,7 +33,7 @@ jobs:
           echo "CPPFLAGS=-I/opt/homebrew/include" >> "$GITHUB_ENV"
           echo "LDFLAGS=-L/opt/homebrew/lib" >> "$GITHUB_ENV"
       - name: checkout APF source code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v5
       - name: run unit tests
         run: |
           make -C unit_tests

.github/workflows/pd-externals.yml

@@ -8,7 +8,7 @@ jobs:
         run: |
           sudo apt-get install --no-install-recommends puredata-dev
       - name: checkout APF
-        uses: actions/checkout@v2
+        uses: actions/checkout@v5
         with:
           submodules: true
           path: apf
@@ -31,7 +31,7 @@ jobs:
         run: |
           brew install --cask pd
       - name: checkout APF
-        uses: actions/checkout@v2
+        uses: actions/checkout@v5
         with:
           submodules: true
           path: apf
@@ -70,7 +70,7 @@ jobs:
           rm -f Pd.zip
           export PD="${PROGRAMFILES}/pd/bin/pd.com"
       - name: checkout APF
-        uses: actions/checkout@v2
+        uses: actions/checkout@v5
         with:
           submodules: true
           path: apf
@@ -91,7 +91,7 @@ jobs:
     needs: [linux, macos, windows]
     steps:
       - name: Clone Git repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v5
       - name: Retrieve Linux externals
         uses: actions/download-artifact@v2
         with: