Add 4x4 3DGS plan to ndarray index #478

Job	Run time
clippy/1.95.0	39s
Pass MSRV values to other jobs	2s
format/stable	21s
nostd/thumbv6m-none-eabi/stable	26s
docs/nightly	52s
native-backend/stable	8m 14s
tier4-avx512-check	28s
hpc-stream-parallel/rayon	1m 22s
miri	1m 3s
nightly-simd-polyfill	41s
cargo-careful	39s
cross_test/${{ matrix.target }}/${{ matrix.rust }}	0s
blas-msrv	50s
tests/stable	11m 36s
tests/beta	10m 45s
tests/1.95.0	11m 14s
conclusion	-1s
	49m 11s

Provide feedback