Tests

ci: add submodules #52

Job	Run time
windows-latest (R-release rust-stable-msvc)	5m 42s
windows-latest (R-devel rust-stable-msvc)	5m 55s
ubuntu-latest w/ bindgen (R-devel rust-stable )	1m 16s
windows-latest (R-oldrel rust-stable-msvc)	10m 55s
macOS-latest w/ bindgen (R-devel rust-stable )	2m 23s
macOS-latest (R-release rust-stable)	2m 9s
windows-latest w/ bindgen (R-release rust-stable-msvc x86_64-pc-windows-gnu)	4m 49s
ubuntu-latest (R-release rust-stable)	55s
windows-latest w/ bindgen (R-devel rust-stable-msvc x86_64-pc-windows-gnu)	3m 46s
ubuntu-latest (R-release rust-nightly)	1m 28s
windows-latest w/ bindgen (R-release rust-nightly-msvc x86_64-pc-windows-gnu)	4m 6s
ubuntu-latest (R-devel rust-stable)	1m 5s
windows-latest w/ bindgen (R-oldrel rust-nightly-msvc x86_64-pc-windows-gnu)	8m 4s
ubuntu-latest (R-oldrel rust-stable)	1m 17s
	53m 50s

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