Minimize binary size

--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,3 +15,9 @@ repository = "https://gitlab.com/kornelski/mandown.git"
 [dependencies]
 pulldown-cmark = "0.8.0"
 deunicode = "1.1.1"
+
+[profile.release]
+codegen-units = 1
+lto = true
+opt-level = "z"
+panic = "abort"