Handle files with first line shell opts.

[ladar]

Description of the Change

The shell script grammar should be applied to:

#!/bin/bash

and

#!/bin/bash -eu

But with the current release, the latter isn't being matched because the regex requires a new line after sh or bash. This regex tweak fixes that oversight.

[ladar]

@icecream17 thank you for reviewing. It's always nice to see another Texan on GitHub.

@sadick254 can we get this regex tweak merged before the next release? There hasn't been any activity in this repo since April, so reaching since you appear to have commit access. Should I increment the package.json before you merge, or will you handle that?