fix: Fix new pylint warnings.

* `no-self-use` is now an optional value. We don't need to disable it
  manually because it's disabled by default.

* We had some superflous parens in the symmath_check.py file so we
  remove those as well.

pylintrc

@@ -287,7 +287,6 @@ disable =
 	illegal-waffle-usage,
 
 	logging-fstring-interpolation,
-	no-self-use,
 	django-not-available,
 
 [REPORTS]
@@ -385,4 +384,4 @@ int-import-graph =
 [EXCEPTIONS]
 overgeneral-exceptions = builtins.Exception
 
-# 37fb074922e492cc9d7946220ba214f767ee70f1
+# f90fb567b1f44429c280e9de9c5d874fb1d81d25

pylintrc_tweaks

@@ -5,5 +5,4 @@ load-plugins = edx_lint.pylint,pylint_django,pylint_celery
 
 [MESSAGES CONTROL]
 disable+ =
-    no-self-use,
     django-not-available,

symmath/symmath_check.py

@@ -324,7 +324,7 @@ def symmath_check(expect, ans, dynamath=None, options=None, debug=None, xml=None
     #fsym = fsym.simplify()
     #fexpect = fexpect.simplify()
     try:
-        diff = (fexpect - fsym)
+        diff = fexpect - fsym
     except Exception as err:  # lint-amnesty, pylint: disable=broad-except
         diff = None