update cargo version

Author: festelo

CONTRIBUTING.md

@@ -142,9 +142,9 @@ cargo clippy --release -- -D warnings
 The following is a temporary fix. See https://github.com/rust-lang/rust-clippy/issues/5094#issuecomment-579116431
 
 ```
-rustup component add clippy --toolchain nightly-2020-10-06-x86_64-unknown-linux-gnu
-rustup component add clippy-preview --toolchain nightly-2020-10-06-x86_64-unknown-linux-gnu
-cargo +nightly-2020-10-06 clippy-preview -Zunstable-options
+rustup component add clippy --toolchain nightly-2020-12-12-x86_64-unknown-linux-gnu
+rustup component add clippy-preview --toolchain nightly-2020-12-12-x86_64-unknown-linux-gnu
+cargo +nightly-2020-12-12 clippy-preview -Zunstable-options
 ```
 
 #### Clippy and Continuous Integration (CI)
@@ -170,7 +170,7 @@ The styles are defined in the rustfmt.toml configuration file, which was generat
 #### Install RustFmt
 
 ```bash
-rustup component add rustfmt --toolchain nightly-2020-10-06-x86_64-unknown-linux-gnu
+rustup component add rustfmt --toolchain nightly-2020-12-12-x86_64-unknown-linux-gnu
 ```
 
 #### Check Formating Changes that RustFmt before applying them
@@ -215,7 +215,7 @@ substrate-module-new <module-name> <author>
 	so we must manually change this to the latest Rust Nightly version only
 	when it is known to work.
 		```bash
-		rustup toolchain install nightly-2020-10-06
+		rustup toolchain install nightly-2020-12-12
 		rustup update stable
 		rustup target add wasm32-unknown-unknown --toolchain nightly
 		```
@@ -225,7 +225,7 @@ substrate-module-new <module-name> <author>
 	and because developers may forget to update to the latest version of Rust
 	Nightly locally. So the solution is to install a specific version of
 	Rust Nightly in .github/workflows/rust.yml (i.e.
-	`rustup toolchain install nightly-2020-10-06`), since for example
+	`rustup toolchain install nightly-2020-12-12`), since for example
 	the latest Rust Nightly version nightly-2020-02-20 may cause our CI tests
 	to fail (i.e. https://github.com/DataHighway-DHX/node/issues/32)
 

scripts/init.sh

@@ -6,7 +6,7 @@ echo "*** Initializing WASM build environment"
 
 rustup update stable
 rustup update nightly
-rustup toolchain install nightly-2020-10-06
-rustup target add wasm32-unknown-unknown --toolchain nightly-2020-10-06
-rustup default nightly-2020-10-06
-rustup override set nightly-2020-10-06
+rustup toolchain install nightly-2020-12-12
+rustup target add wasm32-unknown-unknown --toolchain nightly-2020-12-12
+rustup default nightly-2020-12-12
+rustup override set nightly-2020-12-12