do not pin explicit cookbook versions

we run in an error when using librarian-chef with other cookbooks which requires newer cookbooks (e.g. git). I don't think this cookbook ultimately requires an explicit cookbook version.

```bash
depends "git", "= 1.0.0"
```
leads to an hard to track error:
```bash
persist_resolution_mixin.rb:11:in `persist_resolution': undefined method `correct?' for nil:NilClass (NoMethodError)
```
this (and the other dependencies) should be at least
```bash
depends "git", ">= 1.0.0"
```