Merging fails when multiple licenses are in codemeta.json

[Aidajafarbigloo]

When there are more than one license listed in codemeta.json, the merging process fails. After harvesting metadata from both CITATION.cff and codemeta.json, hermes encounters an error during the merge step, and does not generate hermes.json.

Example codemeta.json:

"license": [
  "https://spdx.org/licenses/Apache-2.0",
  "https://spdx.org/licenses/CC-BY-4.0",
  "https://spdx.org/licenses/CC0-1.0"
]

CITATION.cff:

license: Apache-2.0

The licenses are correctly harvested, but the merging process fails when multiple licenses are presented in the harvest results, and the hermes.json file is not created.

[Aidajafarbigloo]

Related to: HERMES produces incorrect license output when harvested metadata contains multiple licenses #437