Adds explicit requirements to ensure correct dependencies are installed
There was a another comment asking about the numpy < 2 requirement.  It's due to the use of `numpy.sctypes()` which has been removed from NumPy 2.  (As have the scalar type predicates, `issctype()` and `issubsctype()`.)

This occurs inside the ClusteringDiarizer:

```
  File "/code/nemo/t/lib/python3.10/site-packages/nemo/collections/asr/parts/preprocessing/segment.py", line 258, in _convert_samples_to_float32
    if samples.dtype in np.sctypes['int']:
  File "/code/nemo/t/lib/python3.10/site-packages/numpy/__init__.py", line 397, in __getattr__
    raise AttributeError(
AttributeError: `np.sctypes` was removed in the NumPy 2.0 release. Access dtypes explicitly instead.. Did you mean: 'dtypes'?
```

It does not appear to be used in many locations:

```
$ grep -r 'in .*\.sctypes' .
./nemo/collections/asr/parts/preprocessing/feature_loader.py:        if samples.dtype in np.sctypes['int']:
./nemo/collections/asr/parts/preprocessing/feature_loader.py:        elif samples.dtype in np.sctypes['float']:
./nemo/collections/asr/parts/preprocessing/segment.py:        if samples.dtype in np.sctypes['int']:
./nemo/collections/asr/parts/preprocessing/segment.py:        elif samples.dtype in np.sctypes['float']:
```

I experimented, and I believe this could be changed to use `issubdtype()` which is present in both NumPy 1.x and 2.  I could look more closely at NumPy 2 in another PR.  ~~It might be nice to start moving NeMo toward it, as it seems NumPy 2 has significant improvements.  LMK.~~

Aside from NeMo code, NumPy 2 will at least need Tensorboard >= 2.18, for its update to NumPy 2 ([done](https://github.com/tensorflow/tensorboard/commit/b163c5df852f08468013fb292bff854e5f49add0) but not released).

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# What does this PR do ?

Numpy 1.x is required, but 2 (latest) will be installed if it is not present.  IPython is also required, but not listed as a requirement.  Explicit requirements also make it possible to use `pip install nemo_toolkit` without the entire Anaconda distribution installed.

This change is similar to #9805 , which upper-bounded `huggingface_hub`.

Also include a few trivial typos in the tutorial notebooks.

**Collection**: [Note which collection this PR will affect]

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