Can't subscript generic Enum parameters

[lacusdoloris]

Describe the Bug

Enums passed as T: Enum can't be subscripted, even though this is otherwise valid.

Sandbox Link

https://pyrefly.org/sandbox/?project=N4IgZglgNgpgziAXKOBDAdgEwEYHsAeAdAA4CeS4ATrgLYAEM6ArvRDcbpQC50CizNADrphmGGDpdUAa3gB9RiwDaAFUR8BAXQAUAdwAWqLuq6liMVZoCUiYXXt1KMLk0ro6Bo0sEhU2AMY%2BmsLC-lCocHB0AMq0MPws2gk0NnYOfv50ALx0AIwh6MSUEOhc2rE08QLevgFBVsJSsnAKAuVxyVYgADQgZE5gUKSEXLRQFADEdAAKpANDdGhYePh0-rjokADmrkYQG4TCU9EwMHT6XFzEcIgA9Lf94kOEnFu3jLeYuP5wt%2BubEB2lD2G1udDAnDoqAAbqhoH5YGsNttdlx9u5cMQ0Rs4IdCqQuPoNgBaaEwShwdHZOg%2BADMhFyACYfCAAL69VD%2BNFkgBi0BgFCWOAIJHIrKAA

(Only applicable for extension issues) IDE Information

No response