added poetry setup

pyproject.toml

+[tool.poetry]
+name = "ProxPython"
+version = "1.0.4"
+description = ""
+authors = ["Russell Luke <r.luke@math.uni-goettingen.de>"]
+
+[tool.poetry.dependencies]
+python = "^3.8"
+numpy = "^1.19.2"
+scikit-image = "^0.17.2"
+matplotlib = "^3.3.2"
+scipy = "^1.5.2"
+
+[tool.poetry.dev-dependencies]
+
+[build-system]
+requires = ["poetry>=0.12"]
+build-backend = "poetry.masonry.api"