fix venv mkdir error "if already exists"

[HaruNashii]

this fix changes the installer.sh to remove the error log that happens when the user rerun the script, that is a minor error, but for people that is not in the tech world, seeing an "error" in the terminal may be scary

this pr code will remove the "venv directory already exists" warning with the "-p" flag to mkdir:

mkdir -p venv

there is other method that can be more robust, like:
removing the venv directory if exist, and create an new one, to unsure that everything is nicely setted

if [ -d "$PWD/venv" ]; then
	rm -r venv
fi
mkdir venv