function calling fixes for together/llama-3.1

[kwindla]

Fixes for these function call test cases:

test_strings = [
    '<function=hello>{world}</function>',
    '<function=goodbye>{cruel world}"</function>',
    '<function=spacey>{extra space} </function>',
    '<function=noclose>{this has no closing tag}',
    '<function=empty></function>',
]

And also extracts a function call from the middle of an output (not just the beginning).

[LewisWolfgang]

This looks fine to me, but I will leave it to others to approve, as I have not tested function calling with Together.

[vipyne]

this seems pretty stale and the issue is fixed. ok if I close @kwindla ?

[vipyne]

closing for now, but feel free to re-open if necessary @kwindla !