Update shell shebang to be more portable.

build_unicorn.sh

-#!/bin/bash
+#!/usr/bin/env bash
 if [[ ! -d unicorn2 ]]; then
     git clone https://github.com/geohot/unicorn.git -b dev unicorn2
     #git clone https://github.com/unicorn-engine/unicorn.git -b dev unicorn2

demo/challenge_fault.sh

-#!/bin/bash
+#!/usr/bin/env bash
 
 # --- DOC ----------------------------------------------------------------------
 

demo/challenge_simple.sh

-#!/bin/bash
+#!/usr/bin/env bash
 
 # --- DOC ----------------------------------------------------------------------
 

demo/forked_node.sh

-#!/bin/bash
+#!/usr/bin/env bash
 
 # This runs a hardhat node forked from mainnet at the specified block.
 # You need to run this in a separate terminal (or in the background)

mipigo/build.sh

-#!/bin/bash -e
+#!/usr/bin/env bash
+set -e
+
 cd ../minigeth
 export GOOS=linux
 export GOARCH=mips

mipigo/startup/startup.sh

-#!/bin/bash -e
+#!/usr/bin/env bash
+set -e
+
 ../../mipsevm/maketests.py startup.s startup.bin

mipigo/test/testbuild.sh

-#!/bin/bash -e
+#!/usr/bin/env bash
+set -e
+
 export GOOS=linux
 export GOARCH=mips
 export GOMIPS=softfloat

mipsevm/minigeth.sh

-#!/bin/bash -e
+#!/usr/bin/env bash
+set -e
+
 (cd ../ && npx hardhat compile)
 (cd ../mipigo && ./build.sh)
 go build

run_block.sh

-#!/bin/bash -e
+#!/usr/bin/env bash
+set -e
+
 (cd minigeth/ && go build)
 mkdir -p /tmp/cannon
 

sync_minigeth.sh

-#!/bin/bash
+#!/usr/bin/env bash
 FILES=$(grep -v "#" files_minigeth)
 MINIGETH=$PWD/minigeth
 git clone https://github.com/ethereum/go-ethereum.git

test_block_transitions.sh

-#!/bin/bash -e
+#!/usr/bin/env bash
+set -e
+
 (cd minigeth/ && go build)
 mkdir -p /tmp/cannon