## Change Summary

This means `pydantic/__init__.py` is now lazy about all imports using `__getattr__`.

Import performance changes:
### Before

```
code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "import pydantic"
1 loop, best of 1: 29.7 msec per loop
```

```
code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "from pydantic import BaseModel"
1 loop, best of 1: 30.4 msec per loop
```

### After

```
code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "import pydantic"
1 loop, best of 1: 4.8 msec per loop
```

```
(env3112) code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "from pydantic import BaseModel"           
1 loop, best of 1: 18.7 msec per loop
```

Tuna output:

<img width="1421" alt="image" src="https://github.com/pydantic/pydantic/assets/4039449/0a57434e-fdda-4709-8793-d96c0a0ee762">

## Related issue number

As promised in https://github.com/pydantic/pydantic/pull/7423#issuecomment-1733361629.

## Checklist

* [x] The pull request title is a good summary of the changes - it will be used in the changelog
* [ ] Unit tests for the changes exist
* [x] Tests pass on CI
* [ ] Documentation reflects the changes where applicable
* [x] My PR is ready to review, **please add a comment including the phrase "please review" to assign reviewers**


Selected Reviewer: @sydney-runkle
Use `__getattr__` for all package imports, improve import time. ## Change Summary

This means `pydantic/__init__.py` is now lazy about all imports using `__getattr__`.

Import performance changes:
### Before

```
code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "import pydantic"
1 loop, best of 1: 29.7 msec per loop
```

```
code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "from pydantic import BaseModel"
1 loop, best of 1: 30.4 msec per loop
```

### After

```
code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "import pydantic"
1 loop, best of 1: 4.8 msec per loop
```

```
(env3112) code/pydantic 0 ➤ pdm run python -m timeit -n 1 -r 1 "from pydantic import BaseModel"           
1 loop, best of 1: 18.7 msec per loop
```

Tuna output:

<img width="1421" alt="image" src="https://github.com/pydantic/pydantic/assets/4039449/0a57434e-fdda-4709-8793-d96c0a0ee762">

## Related issue number

As promised in https://github.com/pydantic/pydantic/pull/7423#issuecomment-1733361629.

## Checklist

* [x] The pull request title is a good summary of the changes - it will be used in the changelog
* [ ] Unit tests for the changes exist
* [x] Tests pass on CI
* [ ] Documentation reflects the changes where applicable
* [x] My PR is ready to review, **please add a comment including the phrase "please review" to assign reviewers**


Selected Reviewer: @sydney-runkle
#!/usr/bin/env bash

# This script is used to build the documentation on CloudFlare Pages, this is just used for build previews
# A different script with the same name exists on the `docs-site` branch (where pre-built docs live).

set -e
set -x

python3 -V

python3 -m pip install --user pdm

python3 -m pdm install -G docs

python3 -m pdm run python -c 'import docs.plugins.main'

# Adding local symlinks gets nice source locations like
#   pydantic_core/core_schema.py
# instead of
#   .venv/lib/python3.10/site-packages/pydantic_core/core_schema.py
ln -s .venv/lib/python*/site-packages/pydantic_core pydantic_core
ln -s .venv/lib/python*/site-packages/pydantic_settings pydantic_settings
ln -s .venv/lib/python*/site-packages/pydantic_extra_types pydantic_extra_types

python3 -m pdm run mkdocs build

#!/usr/bin/env bash

# This script is used to build the documentation on CloudFlare Pages, this is just used for build previews
# A different script with the same name exists on the `docs-site` branch (where pre-built docs live).

set -e
set -x

python3 -V

python3 -m pip install --user pdm

python3 -m pdm install -G docs

python3 -m pdm run python -c 'import docs.plugins.main'

# Adding local symlinks gets nice source locations like
#   pydantic_core/core_schema.py
# instead of
#   .venv/lib/python3.10/site-packages/pydantic_core/core_schema.py
ln -s .venv/lib/python*/site-packages/pydantic_core pydantic_core
ln -s .venv/lib/python*/site-packages/pydantic_settings pydantic_settings
ln -s .venv/lib/python*/site-packages/pydantic_extra_types pydantic_extra_types

python3 -m pdm run mkdocs build
