schema 1.1.0 and higher can't be retrieved because it is in a different location than earlier schemas

[jspaaks]

This part
https://github.com/citation-file-format/cff-converter-python/blob/232acb23015d449c9441597cd614620270e770c8/cffconvert/citation.py#L133-L144

will be affected by the fact that the schema URL can be in one of two places (not counting Zenodo)
Probably best if I just make a dict based on semver

something like

d= {
   "1.0.1": "https://raw.githubusercontent.com/citation-file-format/schema/1.0.1/CFF-Core/schema.yaml",
   "1.0.2": "https://raw.githubusercontent.com/citation-file-format/schema/1.0.2/CFF-Core/schema.yaml",
   "1.0.3": "https://raw.githubusercontent.com/citation-file-format/schema/1.0.3-1/CFF-Core/schema.yaml",
   "1.1.0": "https://raw.githubusercontent.com/citation-file-format/citation-file-format/master/schema.yaml"
}

I can then retrieve the URL with e.g. d["1.0.3"].