Add dependency on static_assertions

PiperOrigin-RevId: 452721435
diff --git a/WORKSPACE b/WORKSPACE
index 6c0ec0f..0100339 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -62,6 +62,10 @@
         "serde_json": crate.spec(
             version = ">0.0.0",
         ),
+        "static_assertions": crate.spec(
+            features = ["extra-traits"],
+            version = ">0.0.0",
+        ),
         "syn": crate.spec(
             features = ["extra-traits"],
             version = ">0.0.0",