serd: Update to 0.30.2

serd (0.30.2) stable;

  * Fix GCC 4 build
  * Fix colliding blank nodes when parsing TriG
  * Fix missing parse error messages
  * Fix parsing "a" abbreviation without padding whitespace
  * Fix parsing TriG graphs with several squashed trailing dots
  * Fix resolving some URIs against base URIs with no trailing slash
  * Improve build system and CI integration
  * Improve documentation

(nia)