flake8: fix F401 'sys' imported but unused

printer.py is left untouched to reduce chance of conflicts

Author: eric-wieser

galgebra/lt.py

@@ -2,7 +2,6 @@
 Multivector Linear Transformation
 """
 
-import sys
 import inspect
 import types
 import itertools

setup.cfg

@@ -41,8 +41,7 @@ per-file-ignores =
     ./galgebra/ga.py:E231,E231,E266
 
     # E231 missing whitespace after ','
-    # F401 'sys' imported but unused
-    ./galgebra/lt.py:E231,F401
+    ./galgebra/lt.py:E231
 
     # E124 closing bracket does not match visual indentation
     # E125 continuation line with same indent as next logical line