According document of 'What’s New In Python 3.7', 'async' are reserved keywords now.

Code in line 105 of 'odoo/addons/base/ir/ir_qweb/assetsbundle.py' 
`def to_html(self, sep=None, css=True, js=True, debug=False, async=False, url_for=(lambda url: url)):`
will throw SyntaxError out if we launch odoo with this update python.
return not urls.url_parse(url).scheme and not urls.url_parse(url).netloc and not url.startswith('/web/content')
        
        
        
        def get_modules_order():
            if request:
                from odoo.addons.web.controllers.main import module_boot
                return json.dumps(module_boot())
            return '[]'
        template = env['ir.qweb'].render(xmlid, {"get_modules_order": get_modules_order})
        files = []
        remains = []
        for el in html.fragments_fromstring(template):
            if isinstance(el, html.HtmlElement):
                href = el.get('href', '')
                src = el.get('src', '')
                atype = el.get('type')
                media = el.get('media')
                if can_aggregate(href) and (el.tag == 'style' or (el.tag == 'link' and el.get('rel') == 'stylesheet')):
                    if href.endswith('.sass'):
                        atype = 'text/sass'
                    elif href.endswith('.less'):
                        atype = 'text/less'
                    if atype not in ('text/less', 'text/sass'):
                        atype = 'text/css'
                    path = [segment for segment in href.split('/') if segment]
                    filename = get_resource_path(*path) if path else None
                    files.append({'atype': atype, 'url': href, 'filename': filename, 'content': el.text, 'media': media})
                elif can_aggregate(src) and el.tag == 'script':