runtime(zserio): add zserio syntax (#13005)

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index 0cde277..916c0fe 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -516,6 +516,7 @@
 runtime/syntax/xslt.vim			@Boobies
 runtime/syntax/xxd.vim			@cecamp
 runtime/syntax/yacc.vim			@cecamp
+runtime/syntax/zserio.vim		@dpelle
 runtime/syntax/zsh.vim			@chrisbra
 runtime/tutor/tutor.eo			@dpelle
 runtime/tutor/tutor.eo.utf-8		@dpelle