resolve problems from deps upgrade

- downgrade reqwest to 0.11.27
  - fixes problems with missmatched transitive dependencies between it and warp, mainly http
- replace deprecated ripemd160 with ripemd (as specified in the formers readme)
- indexmap: replace deprecated remove with functionally identical swap_remove

src/machine/arithmetic_ops.rs

@@ -17,7 +17,7 @@ use crate::types::*;
 
 use crate::fixnum;
 
-use ordered_float::*;
+use ordered_float::{Float, OrderedFloat};
 
 use std::cmp;
 use std::convert::TryFrom;