Upgrading gh actions to v3

Author: madzak

.github/workflows/build.yml

@@ -27,10 +27,10 @@ jobs:
         python-version: [pypy-3.8, 3.6, 3.7, 3.8, 3.9, '3.10']
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v3
         with:
           python-version: ${{ matrix.python-version }}