fix: pip spoke whl repository platform

Having:
```py
pip.parse(
    hub_name = "pre-commit-hook-{}".format(version),
    python_version = version,
    requirements_lock = "//pre-commit/hook/requirements:lock.txt",
),
```
and using `requirements_lock` attribute will create pip spoke whl
repositories just for the host platform.

This can have potential issues when the repository is platform
dependent and the host platform is different of execution platform
(common case for RBE build).

The change sets pip requirements for different platforms separately.

Specifying platforms as:
  - `"linux_*"`
  - `"osx_*"`
  - `"windows_*"`
allows the pip to create repositories for different platforms and
picks up correct one for the execution platform.