Fix preview version names in release process.

[ZvonimirMatic]

In release action, remove 'v' only from the beginning of the version. Currently it's removing all letters 'v' from the version so v4.0.0-preview.2 is published as 4.0.0-preiew.2.

Found the solution using Chat GPT and this StackOverflow post: https://stackoverflow.com/questions/71630227/github-action-how-to-remove-starting-v-from-variable

Can't really test it, hopefully it works.

Closes #106.

[rmunn]

Variable substitution in Bash is documented here. The # syntax deletes the shortest matching pattern from the beginning of the variable (and ## deletes the longest matching pattern instead). Here there's only one pattern (v) and it's one character long, so the shortest/longest distinction shouldn't matter. So yes, based on my knowledge of Bash syntax, this looks correct to me.