Remove obsolete dev-dependency on itertools

Author: jorendorff

crates/string-offsets/Cargo.toml

@@ -10,6 +10,5 @@ keywords = ["unicode", "positions", "utf16", "characters", "lines"]
 categories = ["algorithms", "data-structures", "text-processing", "development-tools::ffi"]
 
 [dev-dependencies]
-itertools = "0.13"
 rand = "0.8"
 rand_chacha = "0.3"