configure.ac: Require at least srt 1.3.0

Recent commits use defines like SRT_LIVE_DEF_PLSIZE, which are
only available starting with that srt version.

(cherry picked from commit 80b149dd) (edited)
edited:
* 3.0 was restricting to < 1.3.0

Signed-off-by: Steve Lhomme <robux4@ycbcr.xyz>