Updated actions/checkout to v6 (#156)

Co-authored-by: Andrew Murray <radarhere@users.noreply.github.com>

Author: radarhere

.github/workflows/test.yml

@@ -19,7 +19,7 @@ jobs:
         os: [ubuntu-latest]
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v6