Fix mypy issue with wandb.finish() (#3283) #5201

Job	Run time
cpu-tests (ubuntu-latest, 3.8, pytorch)	42m 39s
cpu-tests (ubuntu-latest, 3.8, pytorch-nightly)	43m 42s
cpu-tests (ubuntu-latest, 3.9, pytorch)	22m 13s
cpu-tests (ubuntu-latest, 3.9, pytorch-nightly)	22m 25s
cpu-tests (ubuntu-latest, 3.10, pytorch)	50m 59s
cpu-tests (ubuntu-latest, 3.10, pytorch-nightly)	35m 51s
cpu-tests (ubuntu-latest, 3.11, pytorch)	55m 36s
cpu-tests (ubuntu-latest, 3.11, pytorch-nightly)	23m 24s
cpu-tests (ubuntu-latest, 3.12, pytorch)	39m 45s
cpu-tests (ubuntu-latest, 3.12, pytorch-nightly)	24m 17s
cpu-tests (windows-latest, pytorch, 3.9, 1)	17m 47s
cpu-tests (macos-latest, pytorch, 3.9, 1)	10m 53s
	6h 29m 31s

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