Avoid failing when a dependency is too old

Avoid failing when a dependency is too old

(some of them are pulled in by other dependencies, so
just not including them in d/control doesn't stop them being installed)

Most of the content of this patch was generated by the following Python code:

import pathlib
import re

basedir = pathlib.Path.cwd()
if not (basedir / 'pandas/tests').exists():
    raise FileNotFoundError('must be run from the pandas root')
for source_file in basedir.glob('pandas/**/*.py'):
    with open(source_file, 'r') as fd:
        source_text = fd.read()
    if 'pytest.importorskip' in source_text:
        source_text = re.sub(r'pytest\.importorskip(.*)minversion', r'td.versioned_importorskip\1min_version', source_text)
        source_text = re.sub(r'pytest\.importorskip', r'td.versioned_importorskip', source_text)
        if '_test_decorators as td' not in source_text:
            # add the import if it isn't already present
            source_text, count = re.subn(r'^(import pandas|from pandas.*import)',r'import pandas.util._test_decorators as td\n\1', source_text, count=1, flags=re.MULTILINE)
            if count != 1:
                raise KeyError("failed to add import")
        with open(source_file, 'w') as fd:
            fd.write(source_text)

Author: Rebecca N. Palmer <rebecca_palmer@zoho.com>
Forwarded: no

Gbp-Pq: Name versioned_importorskip.patch