Bump actions/checkout from 3 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

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

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

.github/workflows/main.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Run shellcheck
         run: ./build-single-executable aws-micro-release && shellcheck aws-micro-release
   test-on-vm:
@@ -21,7 +21,7 @@ jobs:
         os: [ubuntu-22.04, ubuntu-20.04, ubuntu-18.04, macos-12, macos-11, macos-10.15]
     steps:
       - name: Check out code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install BATS
         run: "[[ -f /usr/local/bin/bats ]] && brew unlink bats || true ; brew install bats-core"
       - name: Run BATS tests
@@ -34,7 +34,7 @@ jobs:
         container: ["ubuntu:22.04", "ubuntu:20.04", "ubuntu:18.04", "debian:11-slim", "debian:10-slim", "debian:9-slim"]
     steps:
       - name: Check out code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install dependencies and BATS
         run: "apt-get update && apt-get install -y openssl curl file bats xxd"
       - name: Run BATS tests
@@ -47,7 +47,7 @@ jobs:
         container: ["alpine:edge", "alpine:3.16", "alpine:3.15", "alpine:3.14", "alpine:3.13"]
     steps:
       - name: Check out code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Install dependencies and BATS
         run: "apk add --no-cache bash openssl curl file bats"
       - name: Run BATS tests
@@ -67,6 +67,6 @@ jobs:
             curl -L https://kojipkgs.fedoraproject.org//packages/bats/1.7.0/2.fc37/noarch/bats-1.7.0-2.fc37.noarch.rpm -o /tmp/bats.rpm && \
             rpm -i /tmp/parallel.rpm /tmp/bats.rpm
       - name: Check out code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Run BATS tests
         run: bats tests/