fix: fix string to timestamp cast for UTC timestamps #6264

Job	Run time
Lint	36s
ubuntu-latest/rust-test	1m 46s
Build Native Library	1m 44s
Verify TPC-H Results	1s
${{ matrix.profile.name }}/${{ matrix.profile.scan_impl }} [${{ matrix.suite.name }}]	1s
Verify TPC-DS Results (${{ matrix.join }})	1s
	4m 9s

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