missing spv1.6 json in include_str

Author: Firestar99

crates/rustc_codegen_spirv-target-specs/src/include_str.rs

@@ -44,6 +44,10 @@ pub const TARGET_SPECS: &[(&str, &str)] = &[
         "spirv-unknown-spv1.5.json",
         include_str!("../target-specs/spirv-unknown-spv1.5.json"),
     ),
+    (
+        "spirv-unknown-spv1.6.json",
+        include_str!("../target-specs/spirv-unknown-spv1.6.json"),
+    ),
     (
         "spirv-unknown-vulkan1.0.json",
         include_str!("../target-specs/spirv-unknown-vulkan1.0.json"),