Build Failure for [cargo build --release --no-default-features --features "inclnum defaultnum"]

[eNipu]

$cargo build --release --no-default-features --features "inclnum defaultnum"

For the above build command the following error is given.
Here is the cargo version

cargo 1.48.0 (65cbdd2dc 2020-10-14)
rustc 1.48.0 (7eac88abb 2020-11-16)

warning: An explicit [[bench]] section is specified in Cargo.toml which currently
disables Cargo from automatically inferring other benchmark targets.
This inference behavior will change in the Rust 2018 edition and the following
files will be included as a benchmark target:

~Playground/Rust/rust-paillier/benches/helpers.rs
~Playground/Rust/rust-paillier/benches/macros.rs

This is likely to break cargo build or cargo test as these files may not be
ready to be compiled as a benchmark target today. You can future-proof yourself
and disable this warning by adding `autobenches = false` to your [package]
section. You may also move the files to a location where Cargo would not
automatically infer them to be a target, such as in subfolders.

For more information on this warning you can consult
https://github.com/rust-lang/cargo/issues/5330
   Compiling autocfg v1.0.1
   Compiling libc v0.2.80
   Compiling rustc-serialize v0.3.24
   Compiling num-traits v0.2.14
   Compiling num-integer v0.1.44
   Compiling num-iter v0.1.42
   Compiling rand v0.4.6
   Compiling rand v0.3.23
   Compiling num-traits v0.1.43
   Compiling num-bigint v0.1.44
   Compiling num-complex v0.1.43
   Compiling num-rational v0.1.42
   Compiling num v0.1.42
   Compiling paillier v0.1.8-pre (/Users/al-amin/Development/Playground/Rust/rust-paillier)
error[E0554]: `#![feature]` may not be used on the stable release channel
 --> src/lib.rs:1:1
  |
1 | #![feature(test)]
  | ^^^^^^^^^^^^^^^^^

error[E0554]: `#![feature]` may not be used on the stable release channel
 --> src/lib.rs:2:1
  |
2 | #![feature(specialization)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
 --> src/lib.rs:2:12
  |
2 | #![feature(specialization)]
  |            ^^^^^^^^^^^^^^
  |
  = note: `#[warn(incomplete_features)]` on by default
  = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information

error: aborting due to 2 previous errors; 1 warning emitted

For more information about this error, try `rustc --explain E0554`.
error: could not compile `paillier`

To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: build failed