Add `::system_version_bytes()` for uniformity

Other functions will return bytes, so it's weird to only be able to get
the version as a string.

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Unreleased - v0.2.0
 
 ### Added
+- `Rn2903::system_version_bytes()`
 
 ### Changed
 

src/lib.rs

@@ -286,4 +286,11 @@ impl Rn2903 {
         let bytes = self.transact(b"sys get ver")?;
         Ok(bytes_to_string(&bytes))
     } 
+
+    /// Queries the module for its firmware version information.
+    ///
+    /// As `::system_version()`, but returns bytes.
+    pub fn system_version_bytes(&mut self) -> Result<Vec<u8>> {
+        self.transact(b"sys get ver")
+    }
 }