Add black to _utils folder except module_testing

Author: kclowes

tox.ini

@@ -24,7 +24,7 @@ use_parentheses=True
 [flake8]
 max-line-length= 100
 exclude= venv*,.tox,docs,build
-ignore=W503
+ignore=E203,W503
 
 [testenv]
 whitelist_externals=/usr/bin/make
@@ -65,6 +65,7 @@ extras=linter
 commands=
     flake8 {toxinidir}/web3 {toxinidir}/ens {toxinidir}/ethpm {toxinidir}/tests --exclude {toxinidir}/ethpm/ethpm-spec
     black {toxinidir}/ethpm {toxinidir}/web3/auto {toxinidir}/web3/utils --exclude {toxinidir}/ethpm/ethpm-spec --check
+    black {toxinidir}/web3/_utils --exclude {toxinidir}/web3/_utils/module_testing --check
     isort --recursive --check-only --diff {toxinidir}/web3/ {toxinidir}/ens/ {toxinidir}/ethpm/ {toxinidir}/tests/
     mypy -p web3 -p ethpm -p ens --config-file {toxinidir}/mypy.ini