build: Emit a warning when deprecated deflate-miniz is used

Cargo.toml

@@ -16,6 +16,7 @@ Library to support the reading and writing of zip files.
 """
 edition = "2021"
 exclude = ["tests/**", "examples/**", ".github/**", "fuzz/**"]
+build = "src/build.rs"
 
 [workspace.dependencies]
 time = { version = "0.3.36", default-features = false }

src/build.rs

@@ -0,0 +1,7 @@
+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`");
+    }
+}