Description of problem:
The shout2send plugin has webm support disabled.

Version-Release number of selected component (if applicable):
shout2send 1.14.0

How reproducible:
Check shout2send with gst-inspect or try to use shout2send together with webm.

Steps to Reproduce:
1. Observe missing video/webm pad capability
   $ gst-inspect-1.0 shout2send | sed -n '/Capabilities/,/^$/p'
2. Observe failing command
   $ gst-launch-1.0 videotestsrc ! vp9enc ! webmmux ! shout2send

Actual results:
shout2send sink pad does not accept video/webm

Expected results:
shout2send sink pad does accept video/webm

Additional info:
The SHOUT_FORMAT_WEBM define is required to enable webm support

https://github.com/GStreamer/gst-plugins-good/blob/c0195300919af46964884de6b4bbd5df7fb8c211/ext/shout2/gstshout2.c#L92