Doc: Missing backquotes. (GH-11982)

Author: JulienPalard

Doc/library/unittest.rst

@@ -2083,7 +2083,7 @@ Loading and running tests
 
    .. method:: run(test)
 
-      This method is the main public interface to the `TextTestRunner`. This
+      This method is the main public interface to the ``TextTestRunner``. This
       method takes a :class:`TestSuite` or :class:`TestCase` instance. A
       :class:`TestResult` is created by calling
       :func:`_makeResult` and the test(s) are run and the