Remove version constraint for Eigen3 package for Eigen3 5.0.0 compat

[traversaro]

Without this fix, configuration against Eigen 5 fails with:

CMake Error at cmake/OsqpEigenDependencies.cmake:14 (find_package):
  Could not find a configuration file for package "Eigen3" that is compatible
  with requested version "3.2.92".

  The following configuration files were considered but not accepted:

    /home/runner/work/robotology-superbuild/robotology-superbuild/.pixi/envs/default/share/eigen3/cmake/Eigen3Config.cmake, version: 5.0.0

Call Stack (most recent call first):

see https://gitlab.com/libeigen/eigen/-/issues/2972 for more details. As Eigen 3.3 was released in 2016, I think we are fine in just asking for Eigen without checking the version of it.

xref: conda-forge/eigen-feedstock#47
xref: robotology/robotology-superbuild#1902
xref: robotology/robotology-superbuild#1903