Use sha256 instead of sha1 to generate tarball hashes.

utils/releasetools/04_release_hash.sh

 #!/bin/bash
-SHA=$(curl -s http://download.redis.io/releases/redis-${1}.tar.gz | shasum | cut -f 1 -d' ')
-ENTRY="hash redis-${1}.tar.gz sha1 $SHA http://download.redis.io/releases/redis-${1}.tar.gz"
+SHA=$(curl -s http://download.redis.io/releases/redis-${1}.tar.gz | shasum -a 256 | cut -f 1 -d' ')
+ENTRY="hash redis-${1}.tar.gz sha256 $SHA http://download.redis.io/releases/redis-${1}.tar.gz"
 echo $ENTRY >> ~/hack/redis-hashes/README
 vi ~/hack/redis-hashes/README
 echo "Press any key to commit, Ctrl-C to abort)."