FIX #649: get latest version for chrome when it's not installed

[MarcBresson]

see #649

[pep8speaks]

Hello @MarcBresson! Thanks for opening this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file webdriver_manager/drivers/chrome.py:

Line 64:80: E501 line too long (107 > 79 characters) Line 65:80: E501 line too long (92 > 79 characters) Line 66:80: E501 line too long (91 > 79 characters)

[veldhaenchen]

@pep8speaks can we please merge this PR? I checked the whole file an this is not the only PEP 8 issue...

[fcole90]

@SergeyPirogov Can you have a look? :blush:

[NickCrews]

This looks good to me!