chore(deps): update actions/checkout action to v6 (#14)

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

Author: renovate[bot]

.github/workflows/build_tests.yml

@@ -7,7 +7,7 @@ jobs:
   build_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/dev2master.yml

@@ -8,7 +8,7 @@ jobs:
   push_to_master:
     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: dev

.github/workflows/docker_tests.yml

@@ -7,7 +7,7 @@ jobs:
   docker_build_tests:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v6
         with:
           ref: ${{ github.head_ref }}
       - uses: docker-practice/actions-setup-docker@master

.github/workflows/license_tests.yml

@@ -7,7 +7,7 @@ jobs:
   license_tests:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v6
         with:
           ref: ${{ github.head_ref }}
       - name: Setup Python

.github/workflows/publish_docker.yml

@@ -14,7 +14,7 @@ jobs:
       packages: write
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v6
         with:
           ref: ${{ github.ref }}