Minimize size of the resulting binary.

--- a/Cargo.toml
+++ b/Cargo.toml
@@ -62,3 +62,9 @@
     ["CHANGELOG.md", "usr/share/doc/interactive-rebase-tool/", "644"],
     ["src/interactive-rebase-tool.1", "usr/share/man/man1/interactive-rebase-tool.1", "644"]
 ]
+
+[profile.release]
+codegen-units = 1
+lto = true
+opt-level = "z"
+panic = "abort"