NearestVersionLocator handles DEFAULT_VERSION_PREFIX as 1 character, but it is a string which can be longer than 1

[omrzljak]

We get
`Execution failed for task ':display_version'.

com.github.zafarkhaja.semver.UnexpectedCharacterException (no error message)`

when we use gitflow config
[gitflow "prefix"] feature = feature/ release = release/ hotfix = hotfix/ support = support/ versiontag = v_

This error occurs in NearestVersionLocator because in line
Version version = Version.valueOf(tag.name[ 0 ] == versionPrefix ? tag.name[ 1..-1 ] : tag.name)

implementation compares only first char of the tag name as versionPrefix. In my config I have prefix "v_" which is 2 is string wiht length 2.