Fix bug with rounding with zoned RelativeTo and increment #2174

Job	Run time
Test FFI (stable, ubuntu-latest)	32s
Test (stable, macos-latest)	40s
Test (stable, ubuntu-latest)	27s
Test (stable, windows-latest)	1m 23s
MSRV	23s
Lint	40s
Documentation	23s
Test feature matrix	12m 13s
	16m 41s

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