Update setup.py

Update setup config to require python 3.9 and 3.10

Author: MagdaJuarez

setup.py

@@ -56,7 +56,7 @@
             # "xesmf>=0.3.0",  # Optional. Not part of main package
             # "esmpy>=8.0.0",  # Optional. Not part of main package
         ],
-        "python_requires": ">=3.8,<3.11",
+        "python_requires": ">3.8,<3.11",
         "packages": ["coast", "coast.data", "coast._utils", "coast.diagnostics"],
         "include_package_data": True,
         "github": "British-Oceanographic-Data-Centre",