create db directory and correct path

etc/redis.conf

@@ -260,7 +260,7 @@ dbfilename dump.rdb
 # The Append Only File will also be created inside this directory.
 #
 # Note that you must specify a directory here, not a file name.
-dir ../db
+dir ./db
 
 ################################# REPLICATION #################################
 

install_server.sh

@@ -14,6 +14,7 @@ fi
 python3 -m pip install -r requirements
 
 # REDIS #
+mkdir -p db
 test ! -d redis/ && git clone https://github.com/antirez/redis.git
 pushd redis/
 git checkout 5.0