ci: Ban some serde_json features

.deny.toml

@@ -38,6 +38,17 @@ license-files = [
 multiple-versions = "warn"
 wildcards = "deny"
 
+[[bans.features]]
+name = "serde_json"
+# These features all don't make sense to activate from a library as they apply
+# globally to all users of serde_json. Make sure we don't enable them somehow.
+deny = [
+    "arbitrary_precision",
+    "float_roundtrip",
+    "preserve_order",
+    "unbounded_depth",
+]
+
 [sources]
 unknown-registry = "deny"
 unknown-git = "deny"