[tests] add dev-dependency version-sync and use it

Author: stbuehler

Cargo.toml

@@ -27,3 +27,4 @@ serde = { version = "1.0.27", optional = true }
 [dev-dependencies]
 serde_test = "1.0.27"
 bincode = "0.9.2"
+version-sync = "0.5"

tests/version-numbers.rs

@@ -0,0 +1,12 @@
+#[macro_use]
+extern crate version_sync;
+
+#[test]
+fn test_readme_deps() {
+	assert_markdown_deps_updated!("README.md");
+}
+
+#[test]
+fn test_html_root_url() {
+	assert_html_root_url_updated!("src/lib.rs");
+}