Set required version for "poetry-core" to "~= 1.0"

Author: sinoroc

setup.cfg

@@ -34,7 +34,7 @@ url = https://pypi.org/project/tox-poetry-dev-dependencies/
 [options]
 install_requires =
     importlib-metadata
-    poetry-core
+    poetry-core ~= 1.0
     tox
 package_dir =
     = src