python_stdlib: update for 3.14 (#18014)

## Summary

Added version 3.14 to the script generating the `known_stdlib.rs` file.

Rebuilt the known stdlibs with latest version (2025.5.10) of [stdlibs
Python lib](https://pypi.org/project/stdlibs/) (which added support for
3.14.0b1).

_Note: Python 3.14 is now in [feature
freeze](https://peps.python.org/pep-0745/) so the modules in stdlib
should be stable._

_See also: #15506_

## Test Plan

The following command has been run. Using for tests the `compression`
module which been introduced with Python 3.14.
```sh
ruff check --no-cache --select I001 --target-version py314 --fix
```

With ruff 0.11.9:
```python
import base64
import datetime

import compression

print(base64, compression, datetime)
```

With this PR:
```python
import base64
import compression
import datetime   

print(base64, compression, datetime)
```

scripts/generate_known_standard_library.py

@@ -13,6 +13,7 @@ VERSIONS: list[tuple[int, int]] = [
     (3, 11),
     (3, 12),
     (3, 13),
+    (3, 14),
 ]
 
 with PATH.open("w") as f: