Pin werkzeug for httpbin compatibility

.github/workflows/tests.yaml

@@ -43,8 +43,9 @@ jobs:
       run: |
         sudo apt update
         sudo apt install -y libcurl4-openssl-dev
+    # werkzeug is pinned for httpbin compatibility https://github.com/postmanlabs/httpbin/issues/673
     - name: Install Python deps
-      run: pip install -U ${{ matrix.deps }} pytest pytest-asyncio pytest-httpbin flaky structlog tomli appdirs lxml
+      run: pip install -U ${{ matrix.deps }} pytest pytest-asyncio pytest-httpbin flaky structlog tomli appdirs lxml 'werkzeug<2.1'
     - name: Decrypt keys
       env:
         KEY: ${{ secrets.KEY }}