fix: allow space on jsonschema tags

[nvanheuverzwijn]

I was trying to parse this golang struct:

type Tool struct {
	Environment string `json:"environment,omitempty" jsonschema:"enum=dev, enum=qa, enum=staging, enum=production, enum=other"`
}

and I realized that the enum were not being populated correctly. Turns out I needed to remove the space from the struct. I added a PR to trim the tags if that's something interesting for you guys. Otherwise, I will open another PR with documentation change to reflect that jsonschema should not have any space betweem each tags.

I also added another enum in the test fixtures with spaces. The actual code change is here https://github.com/invopop/jsonschema/pull/147/files#diff-672d1dd2b9193c8818108f625c29ff25feaea4c1c50cc36cfda18108cba3e1b2

[samlown]

This looks useful! Thanks! I do think it would be better however to move the test outside of the mega-example to avoid updating all the fixtures.

[nvanheuverzwijn]

@samlown You are right, much cleaner that way :)