add close method to AudioSource and VideoSource #327

Job	Run time
Formatting	21s
REUSE-3.2	9s
Check for changes	4s
Test (18)	18s
Test (20)	24s
Test (22)	19s
Test (latest)	21s
stable - x86_64-apple-darwin - node@20	6m 51s
stable - aarch64-apple-darwin - node@20	4m 54s
stable - x86_64-pc-windows-msvc - node@20	11m 4s
stable - x86_64-unknown-linux-gnu - node@20	6m 46s
stable - aarch64-unknown-linux-gnu - node@20	10m 13s
Release	0s
	41m 44s

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