CI fails due to dynamic linking errors with Intel MKL during doctests.

[olson-sean-k]

eccebcc disables testing on the beta Rust toolchain due to dynamic linking errors when running doctests. The lapack feature from Theon uses Intel MKL on Linux and for some reason the library fails to load while executing doctests. See this issue.

CI should test against the beta toolchain. Once this issue is resolved, include the beta toolchain in the test matrix again (revert eccebcc).

[olson-sean-k]

This issues had graduated to the stable toolchain. See this failed CI run, for example. There is an upstream issue tracking this against ndarray-linalg. For now, I may restore CI against the beta toolchain. CI will be noisy, but that's probably okay; disabling CI against the beta toolchain was a debatable response in the first place. 😛

[olson-sean-k]

0237224 re-enables CI against the beta Rust toolchain.

[olson-sean-k]

I've renamed this issue so that it can be used to track ongoing CI failures with the context gathered thus far. I plan to close it once the upstream issue is closed and the fix propagates downstream to Theon and Plexus.

[olson-sean-k]

It's unclear when a fix in ndarray-linalg will be released and I have seen dynamic linking errors when directly executing the example binaries. To reduce noise in CI and avoid propagating linking errors, 81a7468 disables LAPACK features (disables Theon's lapack feature and the FacePlane trait implementation). This means that FaceView::plane is no longer available, but I don't consider that an essential API. This should be temporary and these features will be re-enabled once a fix is available.