increase timeout for extension test

Signed-off-by: Jean-Marc Valin <jmvalin@jmvalin.ca>

tests/meson.build

@@ -3,7 +3,7 @@ opus_tests = [
   ['test_opus_api'],
   ['test_opus_decode', [], 60],
   ['test_opus_encode', 'opus_encode_regressions.c', 120],
-  ['test_opus_extensions'],
+  ['test_opus_extensions', 120],
   ['test_opus_padding'],
   ['test_opus_projection'],
 ]