Singular.jl 0.21.1 released

Today Singular.jl 0.21.1 has been released.

Diff since v0.21.0

Merged pull requests:

• adapt to array changes in julia nightly (#732) (@benlorenz)
• Update JLL deps (#741) (@fingolfin)
• Avoid warnings about CMake compatibility (#742) (@fingolfin)

Closed issues:

• Singular doctests crashing with 1.6 (sometimes) nightly (more or less every time) (#641)