Updated SPIRV-Headers submodule

Przemog1 · Przemog1 · commit 29a5e1258e2f · 2023-10-20T14:16:50.000+02:00
diff --git a/external/SPIRV-Headers b/external/SPIRV-Headers
@@ -1 +1 @@
-Subproject commit 7d2c02ba79e836c87c0a4433c21ac7c82fe92d15
+Subproject commit 6ff18790ffcba92068ed60d36de588c1dcdcdfe4
