Update gitea go-sdk to v0.15.0 (#385)

Update "code.gitea.io/sdk/gitea" to latest release

Reviewed-on: https://gitea.com/gitea/tea/pulls/385
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Reviewed-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>
Co-committed-by: 6543 <6543@obermui.de>

vendor/github.com/hashicorp/go-version/version.go

@@ -278,6 +278,14 @@ func comparePrereleases(v string, other string) int {
 	return 0
 }
 
+// Core returns a new version constructed from only the MAJOR.MINOR.PATCH
+// segments of the version, without prerelease or metadata.
+func (v *Version) Core() *Version {
+	segments := v.Segments64()
+	segmentsOnly := fmt.Sprintf("%d.%d.%d", segments[0], segments[1], segments[2])
+	return Must(NewVersion(segmentsOnly))
+}
+
 // Equal tests if two versions are equal.
 func (v *Version) Equal(o *Version) bool {
 	if v == nil || o == nil {