Inconsistent usage of "v" in the released artifact name

[pre]

Release 1.12.1 was released without the v in the version name

• https://github.com/Peripli/service-manager-cli/releases/download/1.12.1/smctl-1.12.1-darwin-amd64.tar.gz

Release v1.12.2 was released with v in the version name

• https://github.com/Peripli/service-manager-cli/releases/download/v1.12.2/smctl-v1.12.2-darwin-amd64.tar.gz

Choose either one, but please keep it consistent. Automated build tools broke in 1.12.2 because the URL changed all of the sudden.