Clarify the dead batteries workaround for Python >= 3.13

```
try:
    import aifc
    import audioop
except ModuleNotFoundError as e:
    raise ModuleNotFoundError("Please run: pip install audioop-lts standard-aifc") from e
```
https://docs.python.org/3.13/whatsnew/3.13.html#whatsnew313-pep594

speech_recognition/__init__.py

@@ -4,8 +4,11 @@
 
 from __future__ import annotations
 
-import aifc
-import audioop
+try:
+    import aifc
+    import audioop
+except ModuleNotFoundError:
+    raise ModuleNotFoundError("Please run: pip install audioop-lts standard-aifc")
 import base64
 import collections
 import hashlib