chore: replace regex with regex-lite, where appropriate (#1200)

As explained on https://crates.io/crates/regex-lite, `regex-lite` is a
lighter alternative to `regex` and seems to be sufficient for our
purposes.

codex-rs/execpolicy/Cargo.toml

@@ -24,7 +24,7 @@ env_logger = "0.11.5"
 log = "0.4"
 multimap = "0.10.0"
 path-absolutize = "3.1.1"
-regex = "1.11.1"
+regex-lite = "0.1"
 serde = { version = "1.0.194", features = ["derive"] }
 serde_json = "1.0.110"
 serde_with = { version = "3", features = ["macros"] }