MEDIUM: h1/violations: restrict valid version strings to "1.0" and "1.1"

MEDIUM: h1/violations: restrict valid version strings to "1.0" and "1.1"

The "invalid-version-string" HTTP violation only permitted to use
versions which are not made of exactly one digit, a dot, and one digit.
But the only versions where such a version is advertised are 1.0 and
1.1, and after them no other version is advertised. This means that the
only valid tokens are exactly 1.0 and 1.1. There's no point in accepting
"0.9", "1.2" nor "2.0" for example, and while haproxy handles them
carefully, some components only look at the second digit, or apply "&1"
to it resulting in 1.2 becoming 1.0 etc. Better be strict on this and
block these ones unless the violation is explicitly accepted. No
visible effect is expected given that the vast majority of servers and
proxies already do not accept other versions.