ci: issue_count: Fix stale reference to master branch

This commit fixes a stale reference to the 'master' branch when
downloading the issue report configuration file.

Note that the 'master' branch is no longer the default
branch -- 'main' is.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
diff --git a/.github/workflows/issue_count.yml b/.github/workflows/issue_count.yml
index 3d9b1ed..5423ef1 100644
--- a/.github/workflows/issue_count.yml
+++ b/.github/workflows/issue_count.yml
@@ -20,7 +20,7 @@
     steps:
     - name: Download configuration file
       run: |
-        wget -q https://raw.githubusercontent.com/$GITHUB_REPOSITORY/master/.github/workflows/issues-report-config.json
+        wget -q https://raw.githubusercontent.com/$GITHUB_REPOSITORY/main/.github/workflows/issues-report-config.json
 
     - name: install-packages
       run: |