v0.34.0

Many thanks to @Saeris, @Jimdooz, @Kenzo-Wada and @sillvva for contributing to this release.

• Add file, function and promise schema
• Add awaitAsync action to await promise in pipeline
• Add operation property to filterItems, findItem, mapItems, reduceItems and sortItem action
• Rename action argument of filterItems, findItem, mapItems, reduceItems and sortItem action to operation
• Rename action argument and property of transform and transformAsync action to operation
• Change and improve implementation of _stringify util