Add license metadata for pypi (#198)

Author: bringhurst

pyproject.toml

@@ -1,3 +1,11 @@
+[project]
+license = {file = "LICENSE"}
+classifiers = [
+    "Programming Language :: Python :: 3",
+    "License :: OSI Approved :: MIT License",
+    "Operating System :: OS Independent",
+]
+
 [tool.black]
 target-version = ['py36']
 exclude = '.*\.ipynb'
@@ -6,4 +14,4 @@ exclude = '.*\.ipynb'
 py_version = 36
 include_trailing_comma = "true"
 line_length = 88
-multi_line_output = 3
+multi_line_output = 3