refactor: use with_context for process spawning error handling

src/digest_engine/program.rs

@@ -51,7 +51,7 @@ impl DigestEngine for DigestEngineProgram {
             .stdin(Stdio::piped())
             .stdout(Stdio::piped())
             .spawn()
-            .context(anyhow!(
+            .with_context(|| anyhow!(
                 "Problem spawning child process: {:?} {:?}",
                 program,
                 args