Remove `source_me.sh`, it's no longer necessary

source_me.sh

-#!/bin/bash
-pathname=$_
-
-if [[ -n "$BASH" && "$pathname" = "$0" ]]; then
-    echo "Remember: you need to run me as 'source ./source_me.sh', not execute it!"
-    return
-fi
-
-if [ -d venv ]; then
-    source venv/bin/activate
-else
-    python3 -m venv venv
-    source venv/bin/activate
-fi