Singular.jl 0.5.6 released

Today Singular.jl 0.5.6 has been released.

Diff since v0.5.5

Merged pull requests:

• fix FunctionField(QQ, n) (#448) (@8d1h)
• supports multiprecision n_Zn (#450) (@tthsqe12)
• Bump dependencies and version number (#455) (@thofma)