fix(dep): Bump useragent to fix HeadlessChrome version

[rkuzsma]

Bump useragent to 2.3.0 to pull in ua-parser/uap-core#263 in which Headless Chrome version detected to be 0.0.0.
Update tests to reflect latest useragent OS major version string identifiers.

Per ua-parser/uap-core#286 , useragent purposely sets the Windows Vista family to Windows and major version to Vista. The change to useragent was intentional, and the maintainer advises upstream consumers to update tests to reflect the change.

Per 3rd-Eden/useragent#120 , there is an open question to change the stringified OS to not include 0 for missing version numbers. For example:

family: 'Windows'
major: 'Vista'
minor:
patch:
patch_minor:

would display as "Windows Vista" instead of "Windows Vista.0.0".

That open question not withstanding, this commit is an incremental improvement: You can now see both Chrome Headless version and Windows version information in your console output. In general, useragent consumers that perform int() conversions on 'major' should be aware.

Fixes #2762

[mgol]

AFAIK Karma used to use a newer useragent version but reverted to an older one to avoid the Vista.0.0 issue but not showing a Chrome (even if only headless) version at all seems worse than this purely visual issue.

[mgol]

@rkuzsma Please make sure Travis passes, it's red right now (due to incorrect commit message format from what I see).

[mgol]

Please don't close this PR, though, as you did with #3199 & #3200 as that only splits the discussion and makes changes hard to follow. Instead, amend the commit and push via:

git push --force-with-lease

[rkuzsma]

Thanks, I fixed the commit message and updated the PR. All checks are passing now.