Revert "Expand crate keywords"

This reverts commit e2f1aca.

It turns out that crates.io rejects uploads with more than five
keywords.

Cargo.toml

@@ -6,7 +6,7 @@ description = "Library for word wrapping, indenting, and dedenting strings. Has
 documentation = "https://docs.rs/textwrap/"
 repository = "https://github.com/mgeisler/textwrap"
 readme = "README.md"
-keywords = ["text", "formatting", "wrap", "fill", "typesetting", "unicode", "hyphenation"]
+keywords = ["text", "formatting", "wrap", "typesetting", "hyphenation"]
 categories = ["text-processing", "command-line-interface"]
 license = "MIT"
 edition = "2021"