fix: pin schemathesis version in CI checks (#102)

Author: barjin

.github/workflows/check.yaml

@@ -18,7 +18,7 @@ jobs:
       - uses: actions/setup-python@v5
         with:
           python-version: '3.10'
-      - run: python -m pip install schemathesis
+      - run: python -m pip install schemathesis==3.35.0
       - run: npm install
       - run: npm run build
       - run: npm run test