adding forgotten declarations for the new modules

Author: simdimdim

crates/nu-command/src/math/mod.rs

@@ -9,6 +9,7 @@ mod avg;
 mod ceil;
 mod cos;
 mod cosh;
+mod egamma;
 mod euler;
 mod exp;
 mod floor;
@@ -19,6 +20,7 @@ mod max;
 mod median;
 mod min;
 mod mode;
+mod phi;
 mod pi;
 mod product;
 mod reducers;