Override miniz_oxide to build it with optimizations

Building this crate with optimizations decreases the gzipping
part of `cargo xtask dist` from `30-40s` down to `3s`,
the overhead for `rustc` to apply optimizations is miserable on this background

Cargo.toml

@@ -27,6 +27,11 @@ opt-level = 0
 [profile.release.package.xtask]
 opt-level = 0
 
+# Gzipping the artifacts is up to 10 times faster whith optimizations (`cargo xtask dist`).
+# `miniz_ozide` is the direct dependency of `flate2` which does all the heavy lifting
+[profile.dev.package.miniz_oxide]
+opt-level = 3
+
 [patch.'crates-io']
 # rowan = { path = "../rowan" }