Stop linting tuf/exceptions.py with mypy

Stop linting tuf/exceptions.py with mypy as we are going to use
tuf/api/exceptions.py for exceptions in the new code.

Signed-off-by: Martin Vrachev <[email protected]>

Author: MVrachev

tox.ini

@@ -49,7 +49,7 @@ commands =
     # work, unfortunately each subdirectory has to be ignored explicitly.
     pylint -j 0 tuf --ignore=tuf/api,tuf/api/serialization,tuf/ngclient,tuf/ngclient/_internal
 
-    mypy {[testenv:lint]lint_dirs} tuf/exceptions.py
+    mypy {[testenv:lint]lint_dirs}
 
     bandit -r tuf