input: Write a python function to execute a bash script that runs a Python program with a given input and captures its output.
  assert run_bash_script('program.py', 'example input') == 'expected output'
  assert run_bash_script('hello.py', 'world') == 'Hello, world!'
  assert run_bash_script('sum.py', '2 3') == '5'
output: def run_bash_script(script_name, input_str):
      import subprocess
      result = subprocess.run(['python3', script_name], input=input_str, text=True, capture_output=True)
      return result.stdout.strip()