Remove dependency on lexical crates.

The family of lexical crates have a variety of unresolved safety issues and no activity in the last two years. Considering we're only using it in two places, it makes morse sense to just use the built in conversion for usize and reduce the number of dependencies.

Signed-off-by: David Skidmore <davidskidmore@google.com>

src/policy/Cargo.toml

@@ -9,7 +9,6 @@ edition = "2018"
 [dependencies]
 cc-measurement = { path = "../../deps/td-shim/cc-measurement"}
 crypto = { path = "../crypto" }
-lexical-core = { version = "0.8.3", default-features = false, features = ["write-integers", "write-floats", "parse-integers", "parse-floats"] }
 log = { version = "0.4.13", optional = true }
 serde = { version = "1.0", default-features = false, features = ["derive"]}
 serde_json = { version = "1.0", default-features = false, features = ["alloc"] }

src/policy/src/config.rs

@@ -4,7 +4,6 @@
 
 use alloc::{collections::BTreeMap, fmt::Write, string::String, vec::Vec};
 use core::{mem::size_of, ops, str::FromStr};
-use lexical_core::parse;
 use serde::{
     de::{Error, Visitor},
     Deserialize, Deserializer,
@@ -315,13 +314,13 @@ fn parse_range(input: &str) -> Option<ops::Range<usize>> {
     let start = if parts[0].is_empty() {
         usize::MIN
     } else {
-        parse::<usize>(parts[0].as_bytes()).ok()?
+        usize::from_str(parts[0]).ok()?
     };
 
     let end: usize = if parts[1].is_empty() {
         usize::MAX
     } else {
-        parse::<usize>(parts[1].as_bytes()).ok()?
+        usize::from_str(parts[1]).ok()?
     };
 
     Some(start..end)