Bump actions/checkout from 2 to 4 (#170)

Author: dependabot[bot]

.github/workflows/codecov.yml

@@ -23,7 +23,7 @@ jobs:
         ]
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
       with:
         fetch-depth: '2'
 

.github/workflows/lint.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
@@ -29,7 +29,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: Set up Python
         uses: actions/setup-python@v5
         with: