'= 0.1.0'
will lead to a failure to resolve this requirement as this will be added not as a String but as a Fixnum and later Solve won't be able to find this cookbook in the list of all cookbooks available on Supermarket as they are stored as Strings:
Required artifacts do not exist at the desired version
Missing artifacts: 301
Typically we don't use quotes for cookbook names in inventory.yml file thus having this requirement: sources: