Use of "~" in `--workspace` option attempts to create invalid directory and fails.

[sangee2004]

gptscript version v0.8.2+1b5e068f

Steps to reproduce the problem:

1. Execute script with workspace having "~" - gptscript --disable-cache --workspace=~/data testimagevision.gpt

This fails with following error

2024/06/14 16:28:26 mkdir /Users/sangeethahariharan/gptscript/~: not a directory

%pwd
/Users/sangeethahariharan/gptscript

 % gptscript --disable-cache --workspace=~/data  testimagevision.gpt
2024/06/14 16:28:26 mkdir /Users/sangeethahariharan/gptscript/~: not a directory

 % ls ~/data
browser_session		browser_session_no_js	cow.png			sunset.png		~

[g-linville]

@sangee2004 this should be fixed on main now.

[sangee2004]

Tested with gptscript version - v0.0.0-dev-cb7fa1de-dirty

This issue is not seen anymore.