Fix codecov; add badge

.github/workflows/r.yml

@@ -33,7 +33,7 @@ jobs:
 
     steps:
       - uses: actions/checkout@v3
-      
+
       - name: Set up R ${{ matrix.r }}
         uses: r-lib/actions/setup-r@v2
         with:
@@ -72,4 +72,6 @@ jobs:
         shell: Rscript {0}
 
       - name: Upload coverage reports to Codecov
-        uses: codecov/codecov-action@v3
+          uses: codecov/codecov-action@v5
+          with:
+            token: ${{ secrets.CODECOV_TOKEN }}

README.md

@@ -1,5 +1,7 @@
 # ggfla - GGPlot2 Extension for Fixed-Length Axis
 
+[![R](https://github.com/mvfki/ggfla/actions/workflows/r.yml/badge.svg?branch=main&event=push)](https://github.com/mvfki/ggfla/actions/workflows/r.yml)
+
 This package is initially intended for making scanpy-style short-arrow axis in ggplot2. 
 This package implements what is desired in the most appropriate way--exactly 
 replacing the whole axis line with a fixed-length arrow. Other solutions for