Drop Codecov, keep static coverage badge and clean workflows

Author: ammawla

.github/workflows/test-coverage.yaml

@@ -1,6 +1,6 @@
 # epiRomics: a multi-omics R package to identify and visualize enhancers
 
-[![R-CMD-check](https://github.com/Huising-Lab/epiRomics/actions/workflows/R-CMD-check.yaml/badge.svg)](https://github.com/Huising-Lab/epiRomics/actions/workflows/R-CMD-check.yaml) [![BiocCheck](https://github.com/Huising-Lab/epiRomics/actions/workflows/BiocCheck.yaml/badge.svg)](https://github.com/Huising-Lab/epiRomics/actions/workflows/BiocCheck.yaml) [![Coverage](https://img.shields.io/badge/coverage-98%25-brightgreen)](tests/) [![Codecov](https://codecov.io/gh/Huising-Lab/epiRomics/branch/main/graph/badge.svg)](https://codecov.io/gh/Huising-Lab/epiRomics) [![License: Artistic-2.0](https://img.shields.io/badge/License-Artistic--2.0-blue.svg)](https://opensource.org/licenses/Artistic-2.0) [![Altmetric](https://img.shields.io/badge/Altmetric-10.1101%2F2021.08.19.456732-blue.svg)](https://www.altmetric.com/details/112068712)
+[![R-CMD-check](https://github.com/Huising-Lab/epiRomics/actions/workflows/R-CMD-check.yaml/badge.svg)](https://github.com/Huising-Lab/epiRomics/actions/workflows/R-CMD-check.yaml) [![BiocCheck](https://github.com/Huising-Lab/epiRomics/actions/workflows/BiocCheck.yaml/badge.svg)](https://github.com/Huising-Lab/epiRomics/actions/workflows/BiocCheck.yaml) [![Coverage](https://img.shields.io/badge/coverage-98%25-brightgreen)](tests/) [![License: Artistic-2.0](https://img.shields.io/badge/License-Artistic--2.0-blue.svg)](https://opensource.org/licenses/Artistic-2.0) [![Altmetric](https://img.shields.io/badge/Altmetric-10.1101%2F2021.08.19.456732-blue.svg)](https://www.altmetric.com/details/112068712)
 
 An R package designed to integrate and visualize various levels of epigenomic information, including but not limited to: ChIP, Histone, ATAC, and RNA sequencing. epiRomics is also designed for regulatory network analysis in order to identify enhancer and enhanceosome regions from these data.