Bump actions/checkout from 4 to 6

.github/workflows/citation.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 20
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Check for non-ASCII characters
         run: |
           # Fail immediately if there are any non-ASCII characters in

.github/workflows/client-pypi-release.yaml

@@ -16,7 +16,7 @@ jobs:
       name: pypi
       url: https://pypi.org/p/qiskit-ibm-catalog
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: actions/setup-python@v5
         name: Install Python
         with:

.github/workflows/coverage.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 60
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Python 3.11
         uses: actions/setup-python@v4
         with:

.github/workflows/docs.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 60
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-python@v4
         with:
           python-version: '3.11'

.github/workflows/ecosystem.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 30
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Python 3.11
         uses: actions/setup-python@v4
         with:

.github/workflows/lint.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 30
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Python 3.11
         uses: actions/setup-python@v4
         with:

.github/workflows/test_latest_versions.yml

@@ -27,7 +27,7 @@ jobs:
           - os: windows-latest
             python-version: 3.11
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v4
         with: