More reliably detect Google Chrome version number

Previous method was splitting on the first whitespace, and missing the
version number when it appeared as `"Google Chrome 115.0.234.2342"`
instead of, i.e. `"Chromium 115.0.234.8283"`.

This commit changes the version detection to regex search for
whitespace, then one or more digits followed by a period, then at least
one more digit. Only the first sequence of digits is captured. Unless
Chrome radically changes their version numbering, this should capture
the first group of digits after the reported browser name, which would
be the major version.

archivebox/util.py

@@ -229,7 +229,8 @@ def chrome_args(**options) -> List[str]:
     cmd_args = [options['CHROME_BINARY']]
 
     if options['CHROME_HEADLESS']:
-        if int(CHROME_VERSION.split()[1].split('.')[0]) >= 111:
+        chrome_major_version = int(re.search(r'\s(\d+)\.\d', CHROME_VERSION)[1])
+        if chrome_major_version >= 111:
             cmd_args += ("--headless=new",)
         else:
             cmd_args += ('--headless',)