add tests for serde support

Cargo.toml

@@ -103,7 +103,10 @@ members = ["bench"]
 [profile.bench]
 lto = "thin"
 
+[dev-dependencies]
+serde_json = "1.0.120"
+
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
-features = ["search", "crossterm", "termwiz", "termion"]
+features = ["search", "crossterm", "termwiz", "termion", "serde"]
 rustdoc-args = ["--cfg", "docsrs"]