curl: Avoid using HTTP/2 with curl 8.7.x due to bug in error codes

curl 8.7.x has a bug in HTTP/2 error codes introduced by
commit `0dc036225` (HTTP/2: write response directly, 2024-01-31,
`curl-8_7_0~230`) and fixed by commit `5c59f9142` (http2 + ngtcp2:
pass CURLcode errors from callbacks, 2024-04-18, `curl-8_8_0~181`).

Fixes: #26200