Update python version in setup.py and fixed pypi download badge (#1969)

Author: karan6181

README.md

@@ -29,7 +29,7 @@
         <img alt="PyPi Package Version" src="https://img.shields.io/pypi/v/mosaicml">
     </a>
     <a href="https://pepy.tech/project/mosaicml/">
-        <img alt="PyPi Downloads" src="https://static.pepy.tech/personalized-badge/mosaicml?period=month&units=international_system&left_color=grey&right_color=blue&left_text=Downloads">
+        <img alt="PyPi Downloads" src="https://static.pepy.tech/personalized-badge/mosaicml?period=month&units=international_system&left_color=grey&right_color=blue&left_text=Downloads/month">
     </a>
     <a href="https://docs.mosaicml.com/en/stable/">
         <img alt="Documentation" src="https://readthedocs.org/projects/composer/badge/?version=stable">

setup.py

@@ -228,9 +228,9 @@ def package_files(prefix: str, directory: str, extension: str):
       packages=setuptools.find_packages(exclude=['docker*', 'examples*', 'scripts*', 'tests*']),
       classifiers=[
           'Programming Language :: Python :: 3',
-          'Programming Language :: Python :: 3.7',
           'Programming Language :: Python :: 3.8',
           'Programming Language :: Python :: 3.9',
+          'Programming Language :: Python :: 3.10',
       ],
       install_requires=install_requires,
       entry_points={
@@ -241,7 +241,7 @@ def package_files(prefix: str, directory: str, extension: str):
       },
       extras_require=extra_deps,
       dependency_links=['https://developer.download.nvidia.com/compute/redist'],
-      python_requires='>=3.7',
+      python_requires='>=3.8',
       ext_package='composer',
       cmdclass={'develop': develop})