Upgrade rand_core (#2201)

## Issue Addressed

N/A

## Proposed Changes

Upgrade `rand_core` to latest version to fix https://rustsec.org/advisories/RUSTSEC-2021-0023

Cargo.lock

@@ -601,7 +601,7 @@ dependencies = [
  "parking_lot",
  "proto_array",
  "rand 0.7.3",
- "rand_core 0.5.1",
+ "rand_core 0.6.2",
  "rayon",
  "regex",
  "safe_arith",
@@ -4888,7 +4888,7 @@ checksum = "18519b42a40024d661e1714153e9ad0c3de27cd495760ceb09710920f1098b1e"
 dependencies = [
  "libc",
  "rand_chacha 0.3.0",
- "rand_core 0.6.1",
+ "rand_core 0.6.2",
  "rand_hc 0.3.0",
 ]
 
@@ -4909,7 +4909,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e12735cf05c9e10bf21534da50a147b924d555dc7a547c42e6bb2d5b6017ae0d"
 dependencies = [
  "ppv-lite86",
- "rand_core 0.6.1",
+ "rand_core 0.6.2",
 ]
 
 [[package]]
@@ -4923,9 +4923,9 @@ dependencies = [
 
 [[package]]
 name = "rand_core"
-version = "0.6.1"
+version = "0.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c026d7df8b298d90ccbbc5190bd04d85e159eaf5576caeacf8741da93ccbd2e5"
+checksum = "34cf66eb183df1c5876e2dcf6b13d57340741e8dc255b48e40a26de954d06ae7"
 dependencies = [
  "getrandom 0.2.2",
 ]
@@ -4945,7 +4945,7 @@ version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3190ef7066a446f2e7f42e239d161e905420ccab01eb967c9eb27d21b2322a73"
 dependencies = [
- "rand_core 0.6.1",
+ "rand_core 0.6.2",
 ]
 
 [[package]]

beacon_node/beacon_chain/Cargo.toml

@@ -46,7 +46,7 @@ futures = "0.3.7"
 genesis = { path = "../genesis" }
 integer-sqrt = "0.1.5"
 rand = "0.7.3"
-rand_core = "0.5.1"
+rand_core = "0.6.2"
 proto_array = { path = "../../consensus/proto_array" }
 lru = "0.6.0"
 tempfile = "3.1.0"

beacon_node/beacon_chain/src/test_utils.rs

@@ -15,7 +15,7 @@ use genesis::interop_genesis_state;
 use parking_lot::Mutex;
 use rand::rngs::StdRng;
 use rand::Rng;
-use rand_core::SeedableRng;
+use rand::SeedableRng;
 use rayon::prelude::*;
 use slog::Logger;
 use slot_clock::TestingSlotClock;