All Ruby versions show version x.x.0 in the path instead of actual patch number which makes it seem like the wrong version is being used

This question likely gets asked at least once a month.

The path that we use for Ruby versions does not include the full version, but instead ends with `.0` For example someone using Ruby 2.6.1 might see a path that looks like this:

```
/app/vendor/bundle/ruby/2.6.0/gems/
```

Or someone using Ruby 2.4.5 might see a path that looks like this:

```
/app/vendor/bundle/ruby/2.4.0/gems/
```

This is totally expected and does not indicate any problems. All versions of Ruby 2.6.x will use a folder name of `2.6.0` etc.

While this is expected behavior from the buildpack, it is frequently confusing to customers. We could reduce support burden and customer surprise by making the path contain the actual teeny/patch version.

Begin by locating the buildpack logic that determines the Ruby version directory under vendor/bundle, using the 2.6.1 and 2.4.5 examples as the reproduction. Check the existing buildpack tests or reproduce the path behavior locally. Done means supported Ruby patch versions use their actual patch number in the path without breaking dependency installation.

Written by the indexing model from the issue text.