Fix Rust codegen for AnyType (#7461)

Author: aidanhs

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RustClientCodegen.java

@@ -162,6 +162,7 @@ public RustClientCodegen() {
         typeMapping.put("binary", "crate::models::File");
         typeMapping.put("ByteArray", "String");
         typeMapping.put("object", "serde_json::Value");
+        typeMapping.put("AnyType", "serde_json::Value");
 
         // no need for rust
         //importMapping = new HashMap<String, String>();