Example Ruby buildpack uses `unwrap()` in non-test code

[edmorley]

We should not be using .unwrap() outside of tests.

These were found by the unwrap_used lint (which is about to be enabled across the whole repo).

libcnb.rs/examples/ruby-sample/src/layers/bundler.rs

Lines 55 to 57 in 335b351

	layer_path.to_str().unwrap(),
	"--binstubs",
	layer_path.join("bin").to_str().unwrap(),

libcnb.rs/examples/ruby-sample/src/layers/bundler.rs

Line 96 in 335b351

.args(["config", "--local", "path", layer.path.to_str().unwrap()])

libcnb.rs/examples/ruby-sample/src/layers/bundler.rs

Line 108 in 335b351

layer.path.join("bin").as_path().to_str().unwrap(),

[edmorley]

Wontfix since the Ruby example has been removed in #757.