Update actions/checkout version

Author: zachborboa

.github/workflows/ci.yml

@@ -37,7 +37,7 @@ jobs:
           php-version: ${{ matrix.php-version }}
 
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Test
         run: bash tests/ci.sh

.github/workflows/release.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Install requirements
         run: |