Fix license file format (#48)

Author: adeas31

pyproject.toml

@@ -46,7 +46,7 @@ authors = [
 maintainers = [
     { name = "Adeel Asghar", email = "adeel.asghar@liu.se" }
 ]
-license = { file = "license.txt" }
+license = "LicenseRef-OSMC-PL"
 requires-python = ">=3.12"
 dependencies = [
     "six",
@@ -58,6 +58,9 @@ dependencies = [
     "pandas"
 ]
 
+[tool.setuptools]
+license-files = ["license.txt"]
+
 # include OMSens and all its subpackages
 [tool.setuptools.packages.find]
 where = ["src"]