Grade core string deprecated in Moodle 3.11

[logan-reynolds]

When doing basic operational tests with latest commit of mod_oublog on the MOODLE_39_STABLE branch (version 2020091401 release 3.9 r1) running against Moodle 3.11.2 with PHP 7.4, I'm seeing the following string deprecation warning when going to add an instance to course:

String [grade,core] is deprecated. Either you should no longer be using that string, or the string has been incorrectly deprecated, in which case you should report this as a bug. Please refer to https://docs.moodle.org/dev/String_deprecation

    line 394 of /lib/classes/string_manager_standard.php: call to debugging()
    line 7283 of /lib/moodlelib.php: call to core_string_manager_standard->get_string()
    line 180 of /mod/oublog/mod_form.php: call to get_string()
    line 214 of /lib/formslib.php: call to mod_oublog_mod_form->definition()
    line 130 of /course/moodleform_mod.php: call to moodleform->__construct()
    line 150 of /course/modedit.php: call to moodleform_mod->__construct()

[drobayo]

Maybe this can work here:
mod_form
Change
$mform->addElement('header', 'modstandardgrade', get_string('grade'));
with
$mform->addElement('header', 'modstandardgrade', get_string('gradenoun'));

Change:
mform->addElement('modgrade', 'grade', get_string('grade'));
with
mform->addElement('modgrade', 'grade', get_string('gradenoun'));