Bump actions/checkout to latest version (#42)

* Bump actions/checkout to latest version

This commit bumps the actions/checkout version used in the custom neko
action.

* Use set -e on run commands to cause job failure on intermediate steps

action.yml

@@ -13,7 +13,7 @@ runs:
   using: "composite"
   steps:
     - name: Clone Qiskit/qiskit-neko PUBLIC repository
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
       with:
         repository: Qiskit/qiskit-neko
         path: qiskit-neko
@@ -26,11 +26,12 @@ runs:
         pip install ./qiskit-neko
       shell: bash
     - name: Checkout base repository
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
       with:
         path: repo_under_test
     - name: Install repo under test
       run: |
+        set -e
         pushd repo_under_test
         ${{ inputs.repo_install_command }}
         popd
@@ -39,6 +40,7 @@ runs:
       env:
         PYTHONWARNINGS: default
       run: |
+        set -e
         cd qiskit-neko
         stestr run ${{ inputs.test_selection }}
       shell: bash