Update tox from 3.9.0 to 3.10.0 (#11409)

requirements/travis_base.txt

@@ -7,9 +7,9 @@ wheel==0.33.4 \
 setuptools==41.0.1 \
     --hash=sha256:a222d126f5471598053c9a77f4b5d4f26eaa1f150ad6e01dcf1a42e185d05613 \
     --hash=sha256:c7769ce668c7a333d84e17fe8b524b1c45e7ee9f7908ad0a73e1eda7e6a5aebf
-tox==3.9.0 \
-    --hash=sha256:1b166b93d2ce66bb7b253ba944d2be89e0c9d432d49eeb9da2988b4902a4684e \
-    --hash=sha256:665cbdd99f5c196dd80d1d8db8c8cf5d48b1ae1f778bccd1bdf14d5aaf4ca0fc
+tox==3.10.0 \
+    --hash=sha256:5d6b9e7ad99a93b00ecd509e13552600d38eedd2b035ba24709f850b23f51254 \
+    --hash=sha256:fee5b4fa2fb1638b57879a1fcaefbfd16201d8d7ecb9956406855a85d518ac4c
 
 # Dependencies of Tox
 virtualenv==16.5.0 \