Update CI after renaming master branch to main.

.github/workflows/ci.yml

@@ -4,7 +4,7 @@ name: CI
 on:
   push:
     branches:
-      - master
+      - main
     tags:
       - '**'
   pull_request:
@@ -52,7 +52,7 @@ jobs:
         run: |
           python --version
           echo "Installing additional pip packages"
-          # we install ctapipe using pip to be able to select any commit, e.g. the current master
+          # we install ctapipe using pip to be able to select any commit, e.g. the current main
           pip install \
              "git+https://github.com/cta-observatory/ctapipe@$CTAPIPE_VERSION" \
               pytest-cov

.github/workflows/release-drafter.yml

@@ -3,7 +3,7 @@ name: Release Drafter
 on:
   push:
     branches:
-      - master
+      - main
 
 jobs:
   update_release_draft:

README.md

@@ -1,4 +1,4 @@
-[![CI](https://github.com/cta-observatory/ctapipe_io_nectarcam/workflows/CI/badge.svg?branch=master)](https://github.com/cta-observatory/ctapipe_io_nectarcam/actions?query=workflow%3ACI+branch%3Amaster)
+[![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)
 
 EventSource Plugin for ctapipe, able to read NectarCam zfits files
 and calibrate them to R1 as needed for ctapipe tools.