Update automerge.yml

[gjtorikian]

Leftover from #374; the whole point was dependencies oughta be kept up-to-date automatically.

[github-actions]

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
./bench.sh ./comrak-b7ef4a4	334.5 ± 15.7	326.3	405.7	2.95 ± 0.14
./bench.sh ./comrak-main	331.0 ± 3.6	325.5	339.0	2.92 ± 0.04
./bench.sh ./pulldown-cmark	113.4 ± 1.0	111.9	115.7	1.00
./bench.sh ./cmark-gfm	120.1 ± 1.1	118.0	122.4	1.06 ± 0.01
./bench.sh ./markdown-it	505.5 ± 12.2	490.7	540.3	4.46 ± 0.11

Run on Mon May 6 16:39:08 UTC 2024