fix codecov badge

README.md

@@ -2,7 +2,7 @@
 
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 [![Documentation Status](https://readthedocs.org/projects/ebtelplusplus/badge/?version=latest)](https://ebtelplusplus.readthedocs.io/en/latest/?badge=latest)
-[![codecov](https://codecov.io/gh/rice-solar-physics/ebtelplusplus/graph/badge.svg?token=8G5H9T5AAH)](https://codecov.io/gh/rice-solar-physics/ebtelplusplus)
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 [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.12675386.svg)](https://doi.org/10.5281/zenodo.12675386)
 
 `ebtelplusplus` is an implementation of the enthalpy-based thermal evolution of loops (EBTEL) model for doing