Fix alignment between the segments and the list of words

[guillaumekln]

This PR fixes the issue described in #1082.

I propose to use a simpler Python loop that iterates over each segment and aggregates the words based on the number of tokens.

[ryanheise]

I'm testing this PR in relation to the SRT flashing in #1072 (reply in thread) and it looks like it fixes that issue:

Using the test case:

$ ffmpeg -t 29 -i https://audio2.redcircle.com/episodes/6b196013-8672-43d9-be52-4332b3207d93/stream.mp3 test.mp3
$ python -m whisper --model base --output_format all --word_timestamps True test.mp3

The SRT flashing would normally appear on punctuation such as block 27 below, where the underline momentarily disappears and it switches from the words to the segment text, but here they match:

25
00:00:19,380 --> 00:00:19,880
Bronx located on the campus of Ryder University<u> in</u> Lawrenceville, New Jersey.

26
00:00:19,880 --> 00:00:20,640
Bronx located on the campus of Ryder University in<u> Lawrenceville,</u> New Jersey.

27
00:00:20,640 --> 00:00:20,840
Bronx located on the campus of Ryder University in Lawrenceville, New Jersey.

28
00:00:20,840 --> 00:00:20,920
Bronx located on the campus of Ryder University in Lawrenceville,<u> New</u> Jersey.

29
00:00:20,920 --> 00:00:21,400
Bronx located on the campus of Ryder University in Lawrenceville, New<u> Jersey.</u>

Before this PR, there was a flash in block 27 shown below:

25
00:00:19,380 --> 00:00:19,880
on the campus of Ryder University<u> in</u> Lawrenceville, New Jersey. A show once restrained

26
00:00:19,880 --> 00:00:20,640
on the campus of Ryder University in<u> Lawrenceville,</u> New Jersey. A show once restrained

27
00:00:20,640 --> 00:00:20,840
Bronx located on the campus of Ryder University in Lawrenceville, New Jersey.

28
00:00:20,840 --> 00:00:20,920
on the campus of Ryder University in Lawrenceville,<u> New</u> Jersey. A show once restrained

29
00:00:20,920 --> 00:00:21,400
on the campus of Ryder University in Lawrenceville, New<u> Jersey.</u> A show once restrained