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

Author: anaconda-renovate[bot]

.github/workflows/tests.yaml

@@ -12,7 +12,7 @@ jobs:
     name: Python ${{ matrix.python-version }}
     steps:
 
-    - uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744 # v3
+    - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
 
     - name: Setup timezone
       uses: zcong1993/setup-timezone@master