CURL_HTTP_VERSION_3, introduced in curl 7.66.0, has changed with curl 7.88.0. Prior 7.88.0, CURL_HTTP_VERSION_3 implies no fallback if error; since 7.88.0, CURL_HTTP_VERSION_3 can fallback to HTTP/1 or HTTP/2. There is a new flag CURL_HTTP_VERSION_3_ONLY that doesn't fallback. See https://github.com/curl/curl/pull/10264.
CURL_HTTP_VERSION_3, introduced in curl 7.66.0, has changed with curl 7.88.0. Prior 7.88.0, CURL_HTTP_VERSION_3 implies no fallback if error; since 7.88.0, CURL_HTTP_VERSION_3 can fallback to HTTP/1 or HTTP/2. There is a new flag CURL_HTTP_VERSION_3_ONLY that doesn't fallback. See https://github.com/curl/curl/pull/10264.
Fixes #519.