chore(deps): update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/integrate.yaml

@@ -27,7 +27,7 @@ jobs:
 
     steps:
     - name: Check out code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Install dependencies
       run: |
@@ -52,7 +52,7 @@ jobs:
           - katib-controller
           - katib-db-manager
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - run: python3 -m pip install tox
       - run: tox -e ${{ matrix.charm }}-unit
 
@@ -78,7 +78,7 @@ jobs:
           - katib-controller
           - katib-db-manager
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Setup operator environment
         uses: charmed-kubernetes/actions-operator@main
         with:
@@ -119,7 +119,7 @@ jobs:
           remove-docker-images: 'true'
 
       - name: Check out code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Setup operator environment
         uses: charmed-kubernetes/actions-operator@main
         with:

.github/workflows/publish.yaml

@@ -32,7 +32,7 @@ jobs:
     outputs:
       charm_paths_list: ${{ steps.get-charm-paths.outputs.CHARM_PATHS_LIST }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with: 
           fetch-depth: 0
           ref: ${{ inputs.source_branch }}
@@ -52,7 +52,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
           ref: ${{ inputs.source_branch }}

.github/workflows/release.yaml

@@ -19,7 +19,7 @@ jobs:
     name: Promote charm
     runs-on: ubuntu-20.04
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Release charm to channel
         uses: canonical/charming-actions/release-charm@2.6.2
         with: