meson: update to version 1.8.1

This adds several improvements to Rust support, including
native clippy and rustdoc targets, the "objects" keyword,
and running doctests.

Require it only when Rust support is requested, to avoid
putting a strict requirement on all build platforms for the
sake of an experimental feature.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

python/scripts/vendor.py

@@ -41,8 +41,8 @@ def main() -> int:
     parser.parse_args()
 
     packages = {
-        "meson==1.5.0":
-        "52b34f4903b882df52ad0d533146d4b992c018ea77399f825579737672ae7b20",
+        "meson==1.8.1":
+        "374bbf71247e629475fc10b0bd2ef66fc418c2d8f4890572f74de0f97d0d42da",
     }
 
     vendor_dir = Path(__file__, "..", "..", "wheels").resolve()