shebang typo in generate_legacy_storage_files.py

[wwuck]

Problem description

The shebang line at the top of https://github.com/pandas-dev/pandas/blob/master/pandas/tests/io/generate_legacy_storage_files.py#L1 has an incorrect interpreter.

It is currently set to /usr/env/bin python

Expected Output

The interpreter should instead be set to /usr/bin/env python

[wwuck]

I noticed this appearing in lintian warning output while packaging a python application with dh-virtualenv.