docs: add avkoll as a contributor for code

[allcontributors[bot]]

Adds @avkoll as a contributor for code.

This was requested by ryansurf in this comment

[github-actions[bot]]

Coverage Report

File	Stmts	Miss	Cover	Missing
src
__init__.py	0	0	100%
api.py	119	7	94%	32–36, 54, 76–77, 109–110
art.py	9	3	67%	32–33, 36
cli.py	25	0	100%
dev_streamlit.py	37	37	0%	1–86
gpt.py	10	6	40%	16–21, 32–45
helper.py	124	38	69%	110, 121–125, 201–209, 221, 234–235, 266, 268–269, 292–293, 356–366, 373–381
send_email.py	24	24	0%	5–48
server.py	47	10	79%	55, 68–71, 87–91, 103–105
settings.py	22	0	100%
streamlit_helper.py	33	33	0%	5–90
TOTAL	450	158	65%

Tests	Skipped	Failures	Errors	Time
11	0 :zzz:	0 :x:	0 :fire:	25.475s :stopwatch: