Use bash instead of dash shell on ubuntu

bin/pyodide

-#!/bin/sh
-set -x
+#!/bin/bash
 
 # get the absolute path to the root directory
-ROOTDIR=$(python -c 'import pathlib, sys; print(pathlib.Path(sys.argv[1]).resolve().parent)' \
+ROOTDIR=$(python -c 'import pathlib, sys; \
+                     print(pathlib.Path(sys.argv[1]).resolve().parents[1])' \
           "${BASH_SOURCE[0]}")
 
 export PYTHONPATH="${PYTHONPATH}:${ROOTDIR}"