Fix exec node test for gh-actions
Fix exec node test for gh-actions

The node adds `shell` to `execOpts` if `/bin/bash` exists. Clearly it
has not existed in Travis or running locally - but it does exist
on gh-action runner, so the test was failing.

mw75/node-red,node-red/node-red,namgk/node-red,namgk/node-red,btsimonh/node-red,mw75/node-red,btsimonh/node-red,mw75/node-red,mw75/node-red,node-red/node-red,btsimonh/node-red,node-red/node-red