Update CI badge

Author: jlenain

README.md

@@ -1,4 +1,4 @@
-[![CI](https://github.com/cta-observatory/ctapipe_io_nectarcam/workflows/CI/badge.svg?branch=main)](https://github.com/cta-observatory/ctapipe_io_nectarcam/actions?query=workflow%3ACI+branch%3Amain)
+[![CI](https://github.com/cta-observatory/ctapipe_io_nectarcam/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/cta-observatory/ctapipe_io_nectarcam/actions/workflows/ci.yml?query=workflow%3ACI+branch%3Amain)
 
 EventSource Plugin for ctapipe, able to read NectarCam zfits files
 and calibrate them to R1 as needed for ctapipe tools.
@@ -14,4 +14,4 @@ conda env create -n nectar-dev -f environment.yml
 conda activate nectar-dev
 pip install -e .
 pre-commit install
-```
+```