Refactor pyproject.toml to use a dictionary for license declaration

pyproject.toml

@@ -1,7 +1,3 @@
-[build-system]
-requires = ["setuptools>=42", "wheel"]
-build-backend = "setuptools.build_meta"
-
 [project]
 name = "medvqa"
 version = "0.13"
@@ -18,7 +14,7 @@ classifiers = [
     "Programming Language :: Python :: 3",
     "Operating System :: OS Independent",
 ]
-license = "MIT"
+license = { text = "MIT" }
 
 [project.scripts]
 medvqa = "medvqa.cli:main"