Use libhex to encode hex string in libs/apkverify/

Bug: 239413416
Test: libapkverify.test, libapkverify.integration_test
Change-Id: I21285b1528f6eb8806a594f53b7b1045255af3b5
Signed-off-by: Tanmoy Mollik <triploblastic@google.com>
diff --git a/libs/apkverify/src/sigutil.rs b/libs/apkverify/src/sigutil.rs
index bfa51c1..395b493 100644
--- a/libs/apkverify/src/sigutil.rs
+++ b/libs/apkverify/src/sigutil.rs
@@ -235,7 +235,7 @@
     use std::fs::File;
     use std::mem::size_of_val;
 
-    use crate::v3::{to_hex_string, APK_SIGNATURE_SCHEME_V3_BLOCK_ID};
+    use crate::v3::APK_SIGNATURE_SCHEME_V3_BLOCK_ID;
 
     const CENTRAL_DIRECTORY_HEADER_SIGNATURE: u32 = 0x02014b50;
 
@@ -276,8 +276,8 @@
         let mut apk_sections = ApkSections::new(apk_file).unwrap();
         let digest = apk_sections.compute_digest(SignatureAlgorithmID::DsaWithSha256).unwrap();
         assert_eq!(
-            "0DF2426EA33AEDAF495D88E5BE0C6A1663FF0A81C5ED12D5B2929AE4B4300F2F",
-            to_hex_string(&digest[..])
+            "0df2426ea33aedaf495d88e5be0c6a1663ff0a81c5ed12d5b2929ae4b4300f2f",
+            hex::encode(&digest[..])
         );
     }