update pt-BR translation
update pt-BR translation

Change-Id: I20a5a12c9e50144fbe9520ca5affc1517babb3f0
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/270463
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>

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