tinypipeline 0.3.0: steps can be defined in non-linear order

This release adds support for pipeline steps being run in non-linear order, specifically as a DAG. If you have four steps defined, you can return a dictionary of keys and list values, where each key is a step, and each list is the set of steps that depend on the key. Example:

# define the pipeline
@pipeline(
    name='test-pipeline', 
    version='0.0.1', 
    description='a test tinypipeline',
)
def pipe():
    # run the steps in the defined order of the graph
    return {
        step_one: [step_two, step_four],
        step_two: [step_three, step_four]
    }

What's Changed

• Add support for nonlinear pipelines by @freddiev4 in #3

Full Changelog: 0.2.0...0.3.0