Add static import to scid.nonlinear

[aleixgg]

There was a missing (static) import of the module std.numeric in the module scid.nonlinear which caused the following DUB warning:

source/scid/nonlinear.d(255,15): Deprecation: module std.numeric is not accessible here, perhaps add 'static import std.numeric;' source/scid/nonlinear.d(255,15): Deprecation: module std.numeric is not accessible here, perhaps add 'static import std.numeric;' source/scid/nonlinear.d(255,15): Deprecation: module std.numeric is not accessible here, perhaps add 'static import std.numeric;' source/scid/nonlinear.d(504,16): Deprecation: module std.numeric is not accessible here, perhaps add 'static import std.numeric;'

[9il]

Thanks!