🚦 Update DYLD path for macos Vulkan

Builds are failing for macOS due to not finding `-lvulkan`; this updates
the `DYLD_LIBRARY_PATH` to include the `$VULKAN_SDK/lib` path, as
required by the vulkan installations.

.github/actions/prepare-runner/action.yaml

@@ -90,6 +90,7 @@ runs:
       run: |
         brew update
         brew install molten-vk
+        echo DYLD_LIBRARY_PATH="${VULKAN_SDK}/lib:${DYLD_LIBRARY_PATH}" > "${GITHUB_ENV}"
 
     - name: Checkout 3rd-party
       uses: ./.github/actions/checkout