async for gtag script

Author: drbruced12

conf.py

@@ -85,7 +85,7 @@ def get_version():
 #
 # This is also used if you do content translation via gettext catalogs.
 # Usually you set "language" from the command line for these cases.
-language = None
+language = 'en'
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
@@ -127,6 +127,10 @@ def get_version():
 # so a file named "default.css" will overwrite the builtin "default.css".
 html_static_path = ['_static']
 
+html_css_files = [
+    'css/rtd_theme_mods.css',
+    ]
+
 # HTML Favicon
 html_favicon = '_static/bridge.ico'
 
@@ -260,8 +264,5 @@ def get_version():
 
 def setup(app):
 
-    app.add_css_file('css/rtd_theme_mods.css')
-
-
-    app.add_js_file('https://www.googletagmanager.com/gtag/js?id=G-QLSP3FJWGT')
+    app.add_js_file('https://www.googletagmanager.com/gtag/js?id=G-QLSP3FJWGT', loading_method="async")
     app.add_js_file(None, body=GA_INVOKE_JS)