Logic to sort the tags was wrong.

Currently the way the tags are sorted is some random order. See the difference below.

**Current way of sorting:** `--sort=-authordate`
```
$ git for-each-ref refs/tags --sort=-authordate --format='%(refname)'
refs/tags/v0.1.10
refs/tags/v0.1.7
refs/tags/v0.1.6
refs/tags/v0.1.4
refs/tags/v0.1.13
refs/tags/v0.1.2
refs/tags/v0.1.3
refs/tags/v0.1.5
refs/tags/v0.1.8
refs/tags/v0.1.0
refs/tags/v0.1.9
refs/tags/v0.1.1
refs/tags/v0.1.11
refs/tags/v0.1.12

```

**After the fix:** `--sort=-*authordate`
```
$ git for-each-ref refs/tags --sort=-*authordate --format='%(refname)'
refs/tags/v0.1.13
refs/tags/v0.1.12
refs/tags/v0.1.11
refs/tags/v0.1.9
refs/tags/v0.1.8
refs/tags/v0.1.5
refs/tags/v0.1.3
refs/tags/v0.1.2
refs/tags/v0.1.1
refs/tags/v0.1.0
refs/tags/v0.1.10
refs/tags/v0.1.6
refs/tags/v0.1.4
refs/tags/v0.1.7
```