UV is incompatible with pyo3 for the reinforcement-learning example

If you create a venv using uv and pip install gymnasium, the example command (`cargo run --example reinforcement-learning --features=pyo3 --package candle-examples -- pg`) will not find any of your installed libraries.

There's a discussion thread about workarounds [here](https://github.com/PyO3/pyo3/issues/4813#issuecomment-2617037553), but the solution of
```
$ find ~/.local/share/uv/python -name "libpython3.xx.dylib"
> /path/to/pythondir/lib/libpython3.xx.dylib
DYLD_FALLBACK_LIBRARY_PATH=/path/to/pythondir/lib/ CARGO_BUILD_RUSTFLAGS="-L /path/to/pythondir/lib/" cargo run --example reinforcement-learning --features=pyo3 --package candle-examples -- pg
```
Gives an error
```
Fatal Python error: init_fs_encoding: failed to get the Python codec of the filesystem encoding
Python runtime state: core initialized
ModuleNotFoundError: No module named 'encodings'

Current thread 0x00000001f8918840 (most recent call first):

```
Which is failing because it is searching for python libs in `\install` which doesn't exist.

## My solution (Mac OS)

This solution is pretty brittle, but it works. It renames the install names of the python libs to point at itself instead of the `/install` directory.

```bash
$ uv venv
$ source .venv/bin/activate
$ uv pip install gymnasium
$ which python3.xx
> /path/to/.venv/bin/python3.xx
$ find ~/.local/share/uv/python -name "libpython3.xx.dylib"
> /path/to/pythondir/lib/libpython3.xx.dylib
$ cp /path/to/pythondir/lib/libpython3.xx.dylib ~/libpython3.xx.dylib.backup
$ install_name_tool -id "/path/to/pythondir/lib/libpython3.xx.dylib" "/path/to/pythondir/lib/libpython3.xx.dylib"
$ otool -L /path/to/pythondir/lib/libpython3.xx.dylib
$ cargo clean
$ export PYTHONHOME=/path/to/pythondir
$ export PYTHONPATH=/path/to/pythondir/lib/python3.xx
$ cargo run --example reinforcement-learning --features=pyo3 --package candle-examples -- pg
```

System Info:
cargo 1.85.1 (d73d2caf9 2024-12-31)
rustc 1.85.1 (4eb161250 2025-03-15)
Apple M3 Max (36 GB)
MacOS 15.3.2
python 3.12.7