This commit adds a support of .srt format to Whisper server. The code is
effectively backported from examples/main. The output mimetype is set to
application/x-subrip as per https://en.wikipedia.org/wiki/SubRip.
Example usage:
curl 127.0.0.1:8080/inference \
-H "Content-Type: multipart/form-data" \
-F file="@<file-path>" \
-F temperature="0.2" \
-F response-format="srt"