Resolve RUSTSEC-2020-0146 (#2242)

## Issue Addressed

Closes #2237

## Proposed Changes

Bump `generic-array` to patched version `0.12.4`

.github/workflows/test-suite.yml

@@ -11,6 +11,8 @@ on:
 env:
   # Deny warnings in CI
   RUSTFLAGS: "-D warnings"
+  # The Nightly version used for cargo-udeps, might need updating from time to time.
+  PINNED_NIGHTLY: nightly-2021-03-01
 jobs:
   target-branch-check:
     name: target-branch-check
@@ -178,8 +180,8 @@ jobs:
     needs: cargo-fmt
     steps:
     - uses: actions/checkout@v1
-    - name: Install a nightly compiler with rustfmt, as a kind of quality control
-      run: rustup toolchain install --component=rustfmt nightly
+    - name: Install Rust (${{ env.PINNED_NIGHTLY }})
+      run: rustup toolchain install $PINNED_NIGHTLY
     - name: Install cargo-udeps
       run: cargo install cargo-udeps --locked
     - name: Run cargo udeps to identify unused crates in the dependency graph

Makefile

@@ -10,6 +10,8 @@ BUILD_PATH_X86_64 = "target/$(X86_64_TAG)/release"
 AARCH64_TAG = "aarch64-unknown-linux-gnu"
 BUILD_PATH_AARCH64 = "target/$(AARCH64_TAG)/release"
 
+PINNED_NIGHTLY ?= nightly
+
 # Builds the Lighthouse binary in release (optimized).
 #
 # Binaries will most likely be found in `./target/release`
@@ -136,11 +138,11 @@ arbitrary-fuzz:
 # Runs cargo audit (Audit Cargo.lock files for crates with security vulnerabilities reported to the RustSec Advisory Database)
 audit:
 	cargo install --force cargo-audit
-	cargo audit --ignore RUSTSEC-2020-0146
+	cargo audit
 
 # Runs `cargo udeps` to check for unused dependencies
 udeps:
-	cargo +nightly udeps --tests --all-targets --release
+	cargo +$(PINNED_NIGHTLY) udeps --tests --all-targets --release
 
 # Performs a `cargo` clean and cleans the `ef_tests` directory.
 clean: