Tests

update libR-sys #54

Job	Run time
ubuntu-latest w/ bindgen (R-devel rust-stable )	1m 30s
windows-latest (R-release rust-stable-msvc)	6m 31s
macOS-latest w/ bindgen (R-devel rust-stable )	2m 35s
windows-latest (R-devel rust-stable-msvc)	6m 17s
windows-latest w/ bindgen (R-release rust-stable-msvc x86_64-pc-windows-gnu)	3m 35s
windows-latest (R-oldrel rust-stable-msvc)	9m 2s
windows-latest w/ bindgen (R-devel rust-stable-msvc x86_64-pc-windows-gnu)	3m 47s
macOS-latest (R-release rust-stable)	2m 26s
windows-latest w/ bindgen (R-release rust-nightly-msvc x86_64-pc-windows-gnu)	3m 37s
windows-latest w/ bindgen (R-oldrel rust-nightly-msvc x86_64-pc-windows-gnu)	9m 21s
ubuntu-latest (R-release rust-stable)	1m 16s
ubuntu-latest (R-release rust-nightly)	1m 1s
ubuntu-latest (R-devel rust-stable)	1m 1s
ubuntu-latest (R-oldrel rust-stable)	1m 15s
	53m 14s

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