Use pydantic-ai-slim version on CLI instead of pydantic-ai

[samuelcolvin]

Without this I'm seeing:

➤ uvx --from 'pydantic-ai-slim[cli]' pai
Traceback (most recent call last):
  File "/Users/samuel/.local/share/uv/python/cpython-3.13.0-macos-aarch64-none/lib/python3.13/importlib/metadata/__init__.py", line 407, in from_name
    return next(iter(cls.discover(name=name)))
StopIteration

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/samuel/Library/Caches/uv/archive-v0/0IvTtIail4E55TFipr14X/bin/pai", line 6, in <module>
    from pydantic_ai._cli import app
  File "/Users/samuel/Library/Caches/uv/archive-v0/0IvTtIail4E55TFipr14X/lib/python3.13/site-packages/pydantic_ai/_cli.py", line 40, in <module>
    __version__ = version('pydantic-ai')
  File "/Users/samuel/.local/share/uv/python/cpython-3.13.0-macos-aarch64-none/lib/python3.13/importlib/metadata/__init__.py", line 987, in version
    return distribution(distribution_name).version
           ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^
  File "/Users/samuel/.local/share/uv/python/cpython-3.13.0-macos-aarch64-none/lib/python3.13/importlib/metadata/__init__.py", line 960, in distribution
    return Distribution.from_name(distribution_name)
           ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^
  File "/Users/samuel/.local/share/uv/python/cpython-3.13.0-macos-aarch64-none/lib/python3.13/importlib/metadata/__init__.py", line 409, in from_name
    raise PackageNotFoundError(name)
importlib.metadata.PackageNotFoundError: No package metadata was found for pydantic-ai

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