Exclude unscriptable-object rule.

Python 3.7 gets this rule wrong for `Generic[]`.

pylint-dev/pylint#2416 tracks this issue in pylint.

.pylintrc

@@ -140,7 +140,8 @@ disable=print-statement,
         deprecated-sys-function,
         exception-escape,
         comprehension-escape,
-        too-few-public-methods
+        too-few-public-methods,
+        unsubscriptable-object
 
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