fix: crash without stackTags

[DennisTruemperMd]

Hi @svdgraaf ,

we are not using the stackTags and are not able to use the new Version of this plugin. The reason is:

Object.entries(this.serverless.service.provider.stackTags) ->

Object.entries(undefined) ->

TypeError: Cannot convert undefined or null to object

Hope this is fix ok for you. We are waiting for the next Version :-)

Have a nice day,
Dennis