MAINT: Coro is not coro-function. (#330)

in the following

```python
async def hello():
    return 1
```

`hello` is a coroutine function, and `hello()` a coroutine.
Fix the vocabulary and ensure that the function is properly used.

Author: Carreau

.pre-commit-config.yaml

@@ -39,3 +39,4 @@ repos:
     hooks:
       - id: ruff
         args: ["--fix"]
+        exclude: script

jupyter_core/utils/__init__.py

@@ -137,15 +137,17 @@ def run_sync(coro: Callable[..., Awaitable[T]]) -> Callable[..., T]:
 
     Parameters
     ----------
-    coro : coroutine
-        The coroutine to be executed.
+    coro : coroutine-function
+        The coroutine-function to be executed.
 
     Returns
     -------
     result :
-        Whatever the coroutine returns.
+        Whatever the coroutine-function returns.
     """
 
+    assert inspect.iscoroutinefunction(coro)
+
     def wrapped(*args, **kwargs):
         name = threading.current_thread().name
         inner = coro(*args, **kwargs)