feat: make runtox script more useful for local dev

Author: untitaker

scripts/runtox.sh

@@ -1,3 +1,8 @@
 #!/bin/sh
-pyversion="$(echo py$TRAVIS_PYTHON_VERSION | sed -e 's/pypypy/pypy/g' -e 's/-dev//g')"
-exec tox -e $(tox -l | grep $pyversion | tr '\n' ',')
+if [ -z "$1" ]; then
+    searchstring="$(echo py$TRAVIS_PYTHON_VERSION | sed -e 's/pypypy/pypy/g' -e 's/-dev//g')"
+else
+    searchstring="$1"
+fi
+
+exec tox -e $(tox -l | grep $searchstring | tr '\n' ',')