Fix test_browser_language_detection after emsdk node update

The new emsdk version of node seems to report `en_US` in
`navigator.languages` (even though the CI machines only have C and POSIX
locales installed).

Author: sbc100

test/test_other.py

@@ -6809,7 +6809,7 @@ def test_browser_language_detection(self):
                       test_file('test_browser_language_detection.c')])
     # We support both "C" and "en_US" here since older versions of node do
     # not expose navigator.languages.
-    lang = os.environ.get('LANG', 'C.UTF-8')
+    lang = os.environ.get('LANG', 'en_US.UTF-8')
     self.assertContained(f'LANG=({lang}|C.UTF-8)', self.run_js('a.out.js'), regex=True)
 
     # Accept-Language: fr,fr-FR;q=0.8,en-US;q=0.5,en;q=0.3