build fails in test_route with PlainTextResponse(url)

[WolfgangFahl]

File "/opt/hostedtoolcache/Python/3.11.2/x64/lib/python3.11/site-packages/starlette/routing.py", line 66, in app
response = await func(request)
^^^^^^^^^^^^^^^^^^^
File "/home/runner/work/justpy/justpy/tests/test_route.py", line 23, in urlFor
return PlainTextResponse(url)
^^^^^^^^^^^^^^^^^^^^^^
File "/opt/hostedtoolcache/Python/3.11.2/x64/lib/python3.11/site-packages/starlette/responses.py", line 55, in init
self.body = self.render(content)
^^^^^^^^^^^^^^^^^^^^
File "/opt/hostedtoolcache/Python/3.11.2/x64/lib/python3.11/site-packages/starlette/responses.py", line 63, in render
return content.encode(self.charset)
^^^^^^^^^^^^^^
AttributeError: 'URL' object has no attribute 'encode'

[WolfgangFahl]

use str() to avoid problem