fix issue with calling get_balanced in the wrong table

[Muscraft]

This fixes an issue where get_balanced would be called in a table that isn't [features] or a dependency table.

To reproduce place below in a Cargo.toml above [features] and try building the docs

[package.metadata.release]
pre-release-replacements = [
  {test="## "},
]

close #10

[ogoffart]

Thanks for the patch!