elm_deps_sync: avoid unwanted diffs

[ento]

Using elm_deps_sync should make minimum changes possible. Either

1. As a direct result of running elm_deps_sync
2. As a result of running elm-package install afterwards inside the spec folder

In order to do so, there are two pieces to take care of:

1. Order of top-level properties of the spec package (version, summary, description, ...): should be what's defined by elm-package.

• This is achieved by preserving the order of the keys when reading the spec file, then writing them back as-is.
• "test-dependencies" is appended as the last property.

2. Order of dependencies: should be what's defined by elm-package (sorted alphabetically)

• This is achieved by sorting dependencies alphabetically when writing back changes.

Other stuff, like matching the JSON format (indentation, etc) with what elm-package outputs, are already taken care of as far as I can see.

[eeue56]

❤️ thanks

[eeue56]

this is a great. please merge and bump the version then bump the version in asset_dependencies

[ento]

Thanks for reviewing!