Fix tag selection on cli make target (#648)

## Description

This change reduces the number of output displayed by `git tag` command.

## Why is this needed

Some commits (like 9c098c1) contains multiple tags, causing issues during the execution of `make cli`.

## How Has This Been Tested?




```bash
$ git clone --depth 1 -b v0.8.0 https://github.com/tinkerbell/tink /tmp/tink
$ cd /tmp/tink
$ make cli
```


## How are existing users impacted? What migration steps/scripts do we need?
NA




## Checklist:

I have:

- [ ] updated the documentation and/or roadmap (if required)
- [ ] added unit or e2e tests
- [ ] provided instructions on how to upgrade

rules.mk

@@ -13,7 +13,7 @@ SHELL := bash
 
 binaries := cmd/tink-cli/tink-cli cmd/tink-controller/tink-controller cmd/tink-server/tink-server cmd/tink-worker/tink-worker cmd/virtual-worker/virtual-worker
 version := $(shell git rev-parse --short HEAD)
-tag := $(shell git tag --points-at HEAD)
+tag := $(shell git tag --points-at HEAD | head -n 1)
 ifneq (,$(tag))
 version := $(tag)-$(version)
 endif