[Checkins] [zopefoundation/ZODB] 1da7a9: .travis.yml: pin setuptools to 49.6 on pypy3

[Jérome Perrin]

  Branch: refs/heads/master
  Home:   https://github.com/zopefoundation/ZODB
  Commit: 1da7a93700bfa53c3558c9033a5ab0701d544f7c
      https://github.com/zopefoundation/ZODB/commit/1da7a93700bfa53c3558c9033a5ab0701d544f7c
  Author: Jérome Perrin <jerome at nexedi.com>
  Date:   2020-09-04 (Fri, 04 Sep 2020)

  Changed paths:
    M .travis.yml

  Log Message:
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  .travis.yml: pin setuptools to 49.6 on pypy3

setutools 50.0.0 does not seem compatible with the pypy3 used on travis.