MNT: Fix classifier in pyproject.toml

Author: snowman2

pyproject.toml

@@ -23,7 +23,7 @@ classifiers = [
     "Development Status :: 4 - Beta",
     "Intended Audience :: Science/Research",
     "License :: OSI Approved :: MIT License",
-    "Operating System :: OS Independe",
+    "Operating System :: OS Independent",
     "Programming Language :: Python",
     "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",