ty_python_semantic: update "no matching overload" diagnostic test

It looks like support for `@overload` has been added since this test was
created, so we remove the TODO and add a snippet (from #274).

crates/ty_python_semantic/resources/mdtest/diagnostics/no_matching_overload.md

@@ -4,11 +4,15 @@
 
 ## Calls to overloaded functions
 
-TODO: Note that we do not yet support the `@overload` decorator to define overloaded functions in
-real Python code. We are instead testing a special-cased function where we create an overloaded
-signature internally. Update this to an `@overload` function in the Python snippet itself once we
-can.
-
 ```py
-type("Foo", ())  # error: [no-matching-overload]
+from typing import overload
+
+@overload
+def f(x: int) -> int: ...
+@overload
+def f(x: str) -> str: ...
+def f(x: int | str) -> int | str:
+    return x
+
+f(b"foo")  # error: [no-matching-overload]
 ```

crates/ty_python_semantic/resources/mdtest/snapshots/no_matching_overload…_-_No_matching_overload…_-_Calls_to_overloaded_…_(3553d085684e16a0).snap

@@ -12,18 +12,31 @@ mdtest path: crates/ty_python_semantic/resources/mdtest/diagnostics/no_matching_
 ## mdtest_snippet.py
 
 ```
-1 | type("Foo", ())  # error: [no-matching-overload]
+ 1 | from typing import overload
+ 2 | 
+ 3 | @overload
+ 4 | def f(x: int) -> int: ...
+ 5 | 
+ 6 | @overload
+ 7 | def f(x: str) -> str: ...
+ 8 | 
+ 9 | def f(x: int | str) -> int | str:
+10 |     return x
+11 | 
+12 | f(b"foo")  # error: [no-matching-overload]
 ```
 
 # Diagnostics
 
 ```
-error[no-matching-overload]: No overload of class `type` matches arguments
- --> src/mdtest_snippet.py:1:1
-  |
-1 | type("Foo", ())  # error: [no-matching-overload]
-  | ^^^^^^^^^^^^^^^
-  |
+error[no-matching-overload]: No overload of function `f` matches arguments
+  --> src/mdtest_snippet.py:12:1
+   |
+10 |     return x
+11 |
+12 | f(b"foo")  # error: [no-matching-overload]
+   | ^^^^^^^^^
+   |
 info: rule `no-matching-overload` is enabled by default
 
 ```