Igniter expects the definition body of Mix.Project#project to be exactly a keywordlist.

**Describe the bug**
In a mix project. If the content of the project function is not a single list, then Igniter can't find the project app and returns an error suggesting that it isn't set.

```
compiling beacon, beacon_live_admin ✔
** (RuntimeError) Failed to parse the application name from mix.exs.

Please ensure that the `project` function in your mix.exs
file returns a keyword list with an `app` key.

(igniter 0.5.27) lib/igniter/project/application.ex:36: anonymous fn/1 in Igniter.Project.Application.app_name/1
(beacon 0.4.1) lib/mix/tasks/beacon.install.ex:93:
```

**To Reproduce**
In a mix project:
```
def project do
version = "0.0.0"
[
app: :my_app,
version: version,
aliases: aliases(),
deps: deps()
]
end
```

**Expected behavior**
I didn't expect that anything would care about anything other than the return value of a function.
Either Igniter should look for the last list in the project function definition,
or - ideally - the return value of the function,
or at least have an error message that states that it expects the body of the project function definition to only be a keyword list.

\*\* Runtime

- Elixir version `1.17.3`
- Erlang version `OTP 27`
- Igniter version `0.5.27`

**Additional context**
Encountered trying to install BeaconCMS

Start at lib/igniter/project/application.ex:36, where app_name/1 fails while parsing mix.exs, and reproduce the issue with the shown project function containing a version variable. Compare the parser's behavior with the expected function return value; done means valid project functions no longer fail to identify the app, or the error clearly documents the supported form.

Written by the indexing model from the issue text.