build: fix compilation without default features (#218)

* build: fix compilation with optional features
* Remove unused config from Cargo.toml
* Fix cache keys
Co-authored-by: Luis Moreno <morenol@users.noreply.github.com>

src/numbers/floatnum.rs

@@ -1,6 +1,6 @@
 use num_traits::{Float, Signed};
 
-use crate::numbers::basenum::Number;
+use crate::{numbers::basenum::Number, rand_custom::get_rng_impl};
 
 /// Defines float number
 /// <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js?config=TeX-AMS_CHTML"></script>
@@ -57,7 +57,7 @@ impl FloatNumber for f64 {
 
     fn rand() -> f64 {
         use rand::Rng;
-        let mut rng = rand::thread_rng();
+        let mut rng = get_rng_impl(None);
         rng.gen()
     }
 
@@ -99,7 +99,7 @@ impl FloatNumber for f32 {
 
     fn rand() -> f32 {
         use rand::Rng;
-        let mut rng = rand::thread_rng();
+        let mut rng = get_rng_impl(None);
         rng.gen()
     }