Type annotations don't work in strict mode with mypy

Python 3.9.5 + mypy 0.812

```python
# magic.py
from jinja2 import Environment
```

```bash
mypy ./magic.py
Success: no issues found in 1 source file
```

```bash
mypy ./magic.py --strict
magic.py:1: error: Module 'jinja2' does not explicitly export attribute 'Environment'; implicit reexport disabled
Found 1 error in 1 file (checked 1 source file)
```

Thanks 👍 