Update to bstr 1.x

Cargo.toml

@@ -7,7 +7,7 @@ authors = [
     "Brandon Williams <bwilliams.eng@gmail.com>",
 ]
 edition = "2018"
-rust-version = "1.41"
+rust-version = "1.60"
 license = "Apache-2.0"
 description = "A diff library for Rust"
 repository = "https://github.com/mitsuhiko/similar"
@@ -23,9 +23,7 @@ default = ["text"]
 text = []
 inline = ["text"]
 
-# this annoyingly currently also turns on bstr and not just bstr/unicode
-# unclear if this is fixable
-unicode = ["text", "unicode-segmentation", "bstr/unicode"]
+unicode = ["text", "unicode-segmentation", "bstr?/unicode", "bstr?/std"]
 bytes = ["bstr", "text"]
 
 [dev-dependencies]