update pt-BR translation
update pt-BR translation

Change-Id: If5ab89a892fc3d50c590ad344c4022a31411299d
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/244107
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>

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