Adding UI test

Author: Cheukting

tests/ui/invalid_pyclass_args.rs

@@ -76,4 +76,13 @@ struct InvalidOrderedStruct {
     inner: i32
 }
 
+#[pyclass]
+struct Example {
+    #[pyo3(foo)]
+    #[pyo3(blah)]
+    x: i32,
+    #[pyo3(pop)]
+    y: i32,
+}
+
 fn main() {}

tests/ui/invalid_pyclass_args.stderr

@@ -221,3 +221,20 @@ note: candidate #2 is defined in an impl for the type `HashOptAndManualHash`
 67 | #[pymethods]
    | ^^^^^^^^^^^^
    = note: this error originates in the attribute macro `pymethods` (in Nightly builds, run with -Z macro-backtrace for more info)
+   error: expected one of: `get`, `set`, `name`
+    --> pytests/src/pyclasses.rs:7:12
+   |
+81 |     #[pyo3(foo)]
+   |            ^^^
+
+ error: expected one of: `get`, `set`, `name`
+  --> pytests/src/pyclasses.rs:8:12
+   |
+82 |     #[pyo3(blah)]
+   |            ^^^^
+
+ error: expected one of: `get`, `set`, `name`
+   --> pytests/src/pyclasses.rs:10:12
+    |
+ 84 |     #[pyo3(pop)]
+    |