Add phpspec 6 support

3.1.0

Allow to use the extension with PHPSpec 6.0 (#4)

Add phpspec 5 and Magento 2.3 support

3.0.0

Add phpspec 5 support to readme

Add phpspec 4.x compatibility

Add phpspec 4.x compatibility.
You need to have at least Magento 2.2 to use this version due to constraints in the Magento metapackage.

Update phpspec dependency version

Originally only phpspec 2.x was supported. however phpspec 3 came out. This release will support phpspec 3.x as well.