Use Redis version 5.0.3. (#3886)

thirdparty/scripts/build_redis.sh

@@ -8,7 +8,7 @@ set -e
 TP_DIR=$(cd "$(dirname "${BASH_SOURCE:-$0}")"; pwd)/../
 
 if [ ! -f $TP_DIR/pkg/redis/src/redis-server ]; then
-  redis_vname="4.0-rc2"
+  redis_vname="5.0.3"
   # This check is to make sure the tarball has been fully extracted. The only
   # relevant bit about redis/utils/whatisdoing.sh is that it is one of the last
   # files in the tarball.