Remove unused version helper (#3086)

lib/version.js

@@ -132,10 +132,6 @@ function slice(v, releaseType) {
   }
 }
 
-function minor(v) {
-  return slice(v, 'minor')
-}
-
 function rangeStart(v) {
   const range = new semver.Range(v, /* loose */ true)
   return range.set[0][0].semver.version
@@ -153,7 +149,6 @@ module.exports = {
   latest,
   listCompare,
   slice,
-  minor,
   rangeStart,
   renderVersionBadge,
 }