build: Fix a bug where cargo syntax is different for MSRV below 1.77.0

src/build.rs

@@ -2,6 +2,6 @@ use std::env::var;
 
 fn main() {
     if var("CARGO_FEATURE_DEFLATE_MINIZ").is_ok() {
-        println!("cargo::warning=Feature `deflate-miniz` is deprecated; replace it with `deflate`");
+        println!("cargo:warning=Feature `deflate-miniz` is deprecated; replace it with `deflate`");
     }
 }