add support for semver crate (#238)

---------

Co-authored-by: Omar Tawfik <15987992+OmarTawfik@users.noreply.github.com>

schemars/tests/semver.rs

@@ -0,0 +1,15 @@
+mod util;
+use schemars::JsonSchema;
+use semver::Version;
+use util::*;
+
+#[allow(dead_code)]
+#[derive(JsonSchema)]
+struct SemverTypes {
+    version: Version,
+}
+
+#[test]
+fn semver_types() -> TestResult {
+    test_default_generated_schema::<SemverTypes>("semver")
+}