disable idn support

tests are failing. on one hand this might require a UNICODE curl build.
we could enable that but then it would need UNICODE support in trurl as
well to accept the non-ASCII test values via the command-line.

```
expected:
'https://xn--rksmrgs-5wao1o.se/\n'
got:
''
104: failed 'https://räksmörgås.se' -g '{puny:host}'
```
Ref: https://github.com/curl/trurl/actions/runs/6863796328/job/18664263891#step:3:4406

.github/workflows/curl-for-win.yml

@@ -35,7 +35,7 @@ jobs:
         run: |
           git clone --depth 1 https://github.com/curl/curl-for-win
           mv curl-for-win/* .
-          export CW_CONFIG='-dev-zero-osnotls-nocurltool-win'
+          export CW_CONFIG='-dev-zero-osnotls-osnoidn-nocurltool-win'
           export CW_REVISION='${{ github.sha }}'
           . ./_versions.sh
           docker trust inspect --pretty "${DOCKER_IMAGE}"