Merge "Update the minversion parameter."

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-minversion = 2.0
+minversion = 3.2.0
 skipsdist = True
 ignore_basepython_conflict = true
 envlist = py36,py37,py38,pep8,samples
@@ -18,7 +18,7 @@ whitelist_externals = find
                       make
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
-install_command = pip install -c ./upper-constraints.txt -U {opts} {packages}
+       -c{toxinidir}/upper-constraints.txt
 usedevelop = True
 commands =
   find . -type f -name "*.pyc" -delete