Update actions/checkout action to v6 (#8)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/build_tests.yml

@@ -16,7 +16,7 @@ jobs:
         python-version: [ 3.7, 3.8, 3.9, "3.10" ]
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v6
       - name: Setup Python
         uses: actions/setup-python@v1
         with:

.github/workflows/license_tests.yml

@@ -12,7 +12,7 @@ jobs:
   license_tests:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v6
       - name: Setup Python
         uses: actions/setup-python@v1
         with:

.github/workflows/publish_stable.yml

@@ -19,7 +19,7 @@ jobs:
     if: success()  # Ensure this job only runs if the previous job succeeds
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v6
         with:
           ref: dev
           fetch-depth: 0 # otherwise, there would be errors pushing refs to the destination repository.
@@ -47,7 +47,7 @@ jobs:
     if: success()  # Ensure this job only runs if the previous job succeeds
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0 # otherwise, there would be errors pushing refs to the destination repository.
           ref: master

.github/workflows/release_workflow.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v6
         with:
           ref: dev
           fetch-depth: 0 # otherwise, there would be errors pushing refs to the destination repository.
@@ -48,7 +48,7 @@ jobs:
     needs: publish_alpha
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v6
       - name: Send message to Matrix bots channel
         id: matrix-chat-message
         uses: fadenb/matrix-chat-message@v0.0.6
@@ -65,7 +65,7 @@ jobs:
     if: success()  # Ensure this job only runs if the previous job succeeds
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v6
         with:
           ref: dev
           fetch-depth: 0 # otherwise, there would be errors pushing refs to the destination repository.
@@ -93,7 +93,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout dev branch
-        uses: actions/checkout@v3
+        uses: actions/checkout@v6
         with:
           ref: dev