ci: upgrade outdated v2 github actions

.github/workflows/sync.yml

@@ -8,7 +8,7 @@ jobs:
   sync:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
         with:
           fetch-depth: 0
       - name: Add remote

.github/workflows/test.yml

@@ -10,9 +10,9 @@ jobs:
   tests:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Set up Python
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v3
         with:
           python-version: 3.9
       - name: Upgrade pip