Add content on deprecating functionality

## Problem
The course covers semantic versioning and breaking changes in Module 7, but lacks content on **deprecation strategies** - a critical skill for package maintainers.

## Proposed Content

Add a section to Module 7 (`07_packaging.qmd`) covering:

### 1. Deprecation Warnings
- Using Python's `warnings` module
- Proper `stacklevel` usage
- **DeprecationWarning vs FutureWarning**:
- `DeprecationWarning`: For developers (filtered by default, shown when running tests)
- `FutureWarning`: For end users (always visible, for changes affecting user code)

### 2. Deprecation Timeline
- Announce in version X.Y
- Remove in version (X+1).0
- Maintain for 1-2 minor releases minimum

### 3. Communication Strategy
- CHANGELOG updates
- Release notes
- Documentation migration guides
- Clear docstring warnings

### 4. Code Examples
```python
import warnings

def old_function(x):
warnings.warn(
"old_function is deprecated and will be removed in version 2.0. "
"Use new_function instead.",
DeprecationWarning,
stacklevel=2
)
return new_function(x)
```

### 5. Real-World Examples
Reference deprecation practices from popular packages (pandas, numpy, scikit-learn).

## Location
Module 7 - after the "Breaking changes" section (around line 132)

Abra o Module 7 em 07_packaging.qmd e leia a seção existente “Breaking changes” por volta da linha 132. Adicione uma seção focada que aborde os tipos de warning e stacklevel, uma linha do tempo de deprecation, práticas de comunicação e exemplos de código e do mundo real. Considera-se concluído quando o módulo explicar claramente essas estratégias e se integrar ao conteúdo ao redor do curso.

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