chore[vortex-duckdb]: allow C++ 20 ext syntax (#3884)

Signed-off-by: Joe Isaacs <[email protected]>
Co-authored-by: Alexander Droste <[email protected]>

Author: joseph-isaacs

vortex-duckdb/build.rs

@@ -204,6 +204,8 @@ fn main() {
         .flag("-Wpedantic")
         // Allow C++20 designator syntax even with C++17 std
         .flag("-Wno-c++20-designator")
+        // Enable C++20 extensions
+        .flag("-Wno-c++20-extensions")
         // Unused parameter warnings are disabled as we include DuckDB
         // headers with implementations that have unused parameters.
         .flag("-Wno-unused-parameter")