fix start timestamp in sentence_info (#2024)

lingji-yidong

2024-08-19 f43da18b5e097515c12438c70fc7918c29e5d0c8

1
2
3
4
5
6
7
8
p m    p.m.
pm    p.m.
p.m.
p.m    p.m.
am    a.m.
a.m.
a.m    a.m.
a m    a.m.