Set Eigen version to 3.4.1 or 4.0.0 once it is released #62
Description
Eigen 3.4.0 was released in August of 2021. While the library has been working perfectly fine for us, there is one little issue that has proven to be quite annoying: Eigen's unit tests are registered with ctest unless we set BUILD_TESTING to OFF because Eigen 3.4.0 does not have an Eigen specific BUILD_TESTING guard. This is actually not something one wants to do (since BUILD_TESTING is the global cmake variable for testing).
However, the 3.4.1 branch (not a tag, this is important) has been updated in July of 2023 with a cmake fix that resolve this. Scion currently uses the July 26, 2023 commit that made this change instead of the original 3.4.0 tag. Once either the 3.4.1 or a higher verison of Eigen is released, we should move to that release as soon as possible.
This issue is opened as a reminder to check for a new Eigen release from time to time. Once a new version of Eigen is released, we can close this issue.