fix stale stateRef

[promer94]

Repo

	react 17	react experimental
#387	https://codesandbox.io/s/swr-387-hspvd	https://codesandbox.io/s/swr-387-concurrent-mode-3j8iy
#463	https://codesandbox.io/s/swr-463-9gtkq	https://codesandbox.io/s/swr-463-concurrent-mode-8ng8g
#789	https://codesandbox.io/s/swr-789-m21g2	https://codesandbox.io/s/swr-789-concurrent-mode-757nt

[codesandbox-ci]

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Latest deployment of this branch, based on commit 8f40976:

Sandbox	Source
SWR-Basic	Configuration
SWR-States	Configuration
SWR-Infinite	Configuration
swr #387	PR
swr #387 concurrent mode	PR
SWR #463	PR
SWR #463 concurrent mode	PR
SWR #789	PR
SWR #789 concurrent mode	PR