docs(README): update badges

README.md

@@ -11,7 +11,7 @@
   <a>![Python 3.7+](https://img.shields.io/badge/Python-3.7%2B-brightgreen.svg)</a>
   <a href="https://pypi.org/project/torchopt">![PyPI](https://img.shields.io/pypi/v/torchopt?logo=pypi)</a>
   <a href="https://github.com/metaopt/torchopt/tree/HEAD/tests">![GitHub Workflow Status](https://img.shields.io/github/actions/workflow/status/metaopt/torchopt/tests.yml?label=tests&logo=github)</a>
-  <a href="https://codecov.io/gh/metaopt/torchopt">![CodeCov](https://img.shields.io/codecov/c/gh/metaopt/torchopt)</a>
+  <a href="https://codecov.io/gh/metaopt/torchopt">![CodeCov](https://img.shields.io/codecov/c/github/metaopt/torchopt/main?logo=codecov)</a>
   <a href="https://torchopt.readthedocs.io">![Documentation Status](https://img.shields.io/readthedocs/torchopt?logo=readthedocs)</a>
   <a href="https://pepy.tech/project/torchopt">![Downloads](https://static.pepy.tech/personalized-badge/torchopt?period=total&left_color=grey&right_color=blue&left_text=downloads)</a>
   <a href="https://github.com/metaopt/torchopt/blob/HEAD/LICENSE">![License](https://img.shields.io/github/license/metaopt/torchopt?label=license&logo=data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZpZXdCb3g9IjAgMCAyNCAyNCIgd2lkdGg9IjI0IiBoZWlnaHQ9IjI0IiBmaWxsPSIjZmZmZmZmIj48cGF0aCBmaWxsLXJ1bGU9ImV2ZW5vZGQiIGQ9Ik0xMi43NSAyLjc1YS43NS43NSAwIDAwLTEuNSAwVjQuNUg5LjI3NmExLjc1IDEuNzUgMCAwMC0uOTg1LjMwM0w2LjU5NiA1Ljk1N0EuMjUuMjUgMCAwMTYuNDU1IDZIMi4zNTNhLjc1Ljc1IDAgMTAwIDEuNUgzLjkzTC41NjMgMTUuMThhLjc2Mi43NjIgMCAwMC4yMS44OGMuMDguMDY0LjE2MS4xMjUuMzA5LjIyMS4xODYuMTIxLjQ1Mi4yNzguNzkyLjQzMy42OC4zMTEgMS42NjIuNjIgMi44NzYuNjJhNi45MTkgNi45MTkgMCAwMDIuODc2LS42MmMuMzQtLjE1NS42MDYtLjMxMi43OTItLjQzMy4xNS0uMDk3LjIzLS4xNTguMzEtLjIyM2EuNzUuNzUgMCAwMC4yMDktLjg3OEw1LjU2OSA3LjVoLjg4NmMuMzUxIDAgLjY5NC0uMTA2Ljk4NC0uMzAzbDEuNjk2LTEuMTU0QS4yNS4yNSAwIDAxOS4yNzUgNmgxLjk3NXYxNC41SDYuNzYzYS43NS43NSAwIDAwMCAxLjVoMTAuNDc0YS43NS43NSAwIDAwMC0xLjVIMTIuNzVWNmgxLjk3NGMuMDUgMCAuMS4wMTUuMTQuMDQzbDEuNjk3IDEuMTU0Yy4yOS4xOTcuNjMzLjMwMy45ODQuMzAzaC44ODZsLTMuMzY4IDcuNjhhLjc1Ljc1IDAgMDAuMjMuODk2Yy4wMTIuMDA5IDAgMCAuMDAyIDBhMy4xNTQgMy4xNTQgMCAwMC4zMS4yMDZjLjE4NS4xMTIuNDUuMjU2Ljc5LjRhNy4zNDMgNy4zNDMgMCAwMDIuODU1LjU2OCA3LjM0MyA3LjM0MyAwIDAwMi44NTYtLjU2OWMuMzM4LS4xNDMuNjA0LS4yODcuNzktLjM5OWEzLjUgMy41IDAgMDAuMzEtLjIwNi43NS43NSAwIDAwLjIzLS44OTZMMjAuMDcgNy41aDEuNTc4YS43NS43NSAwIDAwMC0xLjVoLTQuMTAyYS4yNS4yNSAwIDAxLS4xNC0uMDQzbC0xLjY5Ny0xLjE1NGExLjc1IDEuNzUgMCAwMC0uOTg0LS4zMDNIMTIuNzVWMi43NXpNMi4xOTMgMTUuMTk4YTUuNDE4IDUuNDE4IDAgMDAyLjU1Ny42MzUgNS40MTggNS40MTggMCAwMDIuNTU3LS42MzVMNC43NSA5LjM2OGwtMi41NTcgNS44M3ptMTQuNTEtLjAyNGMuMDgyLjA0LjE3NC4wODMuMjc1LjEyNi41My4yMjMgMS4zMDUuNDUgMi4yNzIuNDVhNS44NDYgNS44NDYgMCAwMDIuNTQ3LS41NzZMMTkuMjUgOS4zNjdsLTIuNTQ3IDUuODA3eiI+PC9wYXRoPjwvc3ZnPgo=)</a>