Bump actions/checkout from 2.4.0 to 3 (#22)

Author: dependabot[bot]

.github/workflows/main.yaml

@@ -16,7 +16,7 @@ jobs:
       matrix:
         python-version: [3.8, 3.9]
     steps:
-      - uses: actions/checkout@v2.4.0
+      - uses: actions/checkout@v3
       - name: Setup Python
         uses: actions/[email protected]
         with:
@@ -49,7 +49,7 @@ jobs:
       matrix:
         python-version: [3.9]
     steps:
-      - uses: actions/checkout@v2.4.0
+      - uses: actions/checkout@v3
       - name: Setup Python
         uses: actions/[email protected]
         with:

.github/workflows/pypipublish.yaml

@@ -8,7 +8,7 @@ jobs:
   deploy:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2.4.0
+      - uses: actions/checkout@v3
       - name: Set up Python
         uses: actions/[email protected]
         with: