deps: update SPIRV-Tools for SDK release (#6114)

Bump the SPIRV-Tools version to v2023.6.rc1 to prepare Vulkan SDK release.
2024-01-02 15:56:30 +01:00 · 2024-01-02 15:56:30 +01:00 · 7d2f9c74d5
--- a/external/SPIRV-Headers
+++ b/external/SPIRV-Headers
@ -1 +1 @@
-Subproject commit cca08c63cefa129d082abca0302adcb81610b465
+Subproject commit 1c6bb2743599e6eb6f37b2969acc0aef812e32e3
--- a/external/SPIRV-Tools
+++ b/external/SPIRV-Tools
@ -1 +1 @@
-Subproject commit 2a238ed24dffd84fe3ed2e60d7aa5c28e2acf45a
+Subproject commit f0cc85efdbbe3a46eae90e0f915dc1509836d0fc