Set type spelling issue

[Gerard Gunnewijk]

The new set type Global Series is misspelled in the JSON as : "global serires".

Files affected:

• https://github.com/mtgjson/mtgjson/blob/master/json/GS1.json
• https://github.com/mtgjson/mtgjson/blob/master/shared/set_configs/global_series/GS1.json

[Zach H]

Fixed