add the "SubSolarMass" Label to the Injection Events uploaded via Event Uploader

To distinguish the injection events of SSM and injection events of all-sky in GraceDB, we add a "SubSolarMass" to SSM injection events.

• ligo.gracedb.rest.GraceDb.createEvent can take a str or list[str] for its labels argument, as shown: https://ligo-gracedb.readthedocs.io/en/latest/api.html#ligo.gracedb.rest.GraceDb.createEvent
• we edit the code to keep consistency with EW-code

added 1 commit

• 96160bc2 - correct the label name to match the GraceDB database

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added 1 commit

• ddf3cad4 - take out bracket

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merged