fix build failure caused by data-encoding v2.2.0
fix build failure caused by data-encoding v2.2.0

- hold data-encoding to known working "<= 2.1.2"

.# [why]

data-encoding v2.2.0 causes a build error for '1.31.0-i686-pc-windows-msvc'.

```
cargo +1.31.0-i686-pc-windows-msvc build --target=i686-pc-windows-msvc --all-features
...
error[E0658]: imports can only refer to extern crate names passed with `--extern` on stable channel (see issue #53130)
   --> C:\Users\appveyor\.cargo\registry\src\github.com-1ecc6299db9ec823\data-encoding-2.2.0\src\lib.rs:194:5
    |
187 | / mod prelude {
188 | |     pub use std::borrow::Cow;
189 | | }
    | |_- not an extern crate passed with `--extern`
...
194 |   use prelude::*;
    |       ^^^^^^^
    |
...
```

uutils/coreutils,uutils/coreutils,uutils/coreutils