No need to call gemspec in common_spree_dependencies

Each component Gemfile already calls it
Add index to source columns on spree_adjustments so UpdateAdjustmentStates migration does not take ages to run on large databases

Fixes #4145
Bump activemerchant to 1.42.3
Bump aws-sdk to 1.31.3
Update changelogs
Don't use hard coded assets prefix

Fixes #4156
Remove variant default_scope from Price class this fixes Price must belong to a variant when trying to fetch the price fo a deleted variant

Fixes #4169

Conflicts:
	core/spec/models/spree/variant_spec.rb
Prevents admin js errors by ensuring taxons key in api response

Fixes #4174