Version schema only allows lower case pre-release versions

[valepakh]

Current version pattern in the version.schema.json allows only lower case pre-release version [\da-z\-] while the semver specification allows any case:

Identifiers MUST comprise only ASCII alphanumerics and hyphens [0-9A-Za-z-]

[KalleOlaviNiemitalo]

.NET SDK has known bugs for upper-case versions in tools: dotnet/sdk#24419, dotnet/sdk#39105.
The current pattern at least reduces the risk of users hitting those bugs.

[AArnott]

I'd take a PR that fixes this. But as the current bug protects you from .NET SDK bugs, I agree with @KalleOlaviNiemitalo and am in no personal rush to fix this.