Use upper constraints in pep8 test run

this is to avoid current problem due to
https://github.com/mtreinish/stestr/issues/347
but also make tests more stable in the future.

Related-Issue: PRODX-3456
Change-Id: I867bec362d83ab820aa6b11dc4770d50133ecdbf
(cherry picked from commit 0c3fe6701b6bedaab7de427c1867869e60a5decb)
1 file changed