www/hurl: update to 6.0.0

Full changelog: https://github.com/Orange-OpenSource/hurl/blob/master/CHANGELOG.md#6.0.0

Breaking changes:

• Check that variables do not conflict with existing functions
• Remove deprecated --fail-at-end option
• Change API for setting variable in hurl:🏃:run
• Remove hurlfmt deprecated --format option
• Rename feature flag from vendored-openssl to static-openssl