fix error message logging

[VasilyStepanov]

response.text() is async here, so without await we will get:

Error while getting token from metadata: <coroutine object ClientResponse.text at 0x7f6958452140>

[rekby]

@VasilyStepanov, hello.

Thanks for the fix.

Do you agree with Yandex Contributor License Agreement
https://yandex.ru/legal/cla/?lang=en (in English) and https://yandex.ru/legal/cla/?lang=ru (in Russian).

?

[VasilyStepanov]

Do you agree with Yandex Contributor License Agreement https://yandex.ru/legal/cla/?lang=en (in English) and https://yandex.ru/legal/cla/?lang=ru (in Russian).

?

Yes!

[rekby]

It's perfect!

Fix style issue please:

-                        "Error while getting token from metadata: %s" % await response.text()
+                        "Error while getting token from metadata: %s"
+                        % await response.text()