Github test workflow: run plain phpunit command.

When --coverage-text is added, phpdbg of OS installed version is used,
thus it ignores version matrix, #62

Author: kabalin

.github/workflows/test.yml

@@ -113,6 +113,6 @@ jobs:
             "$MOODLE_BRANCH" != 'MOODLE_310_STABLE' -a \
             "$MOODLE_BRANCH" != 'MOODLE_39_STABLE' ]
         moodle-plugin-ci phpdoc
-        moodle-plugin-ci phpunit --coverage-text
+        moodle-plugin-ci phpunit
         moodle-plugin-ci behat --profile default
         moodle-plugin-ci behat --profile chrome