Remove unused workflow.

.github/workflows/coverity-scan.yml

@@ -1,24 +0,0 @@
-name: Coverity Scan fixes and develop branches on a weekly basis
-
-on:
-  workflow_dispatch:
-  schedule:
-    - cron: "7 3 * * 0"
-
-jobs:
-  coverity:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v2
-
-    - name: Dependencies
-      run: sudo apt-get install -y libcjson-dev libsqlite3-dev libssl-dev uthash-dev
-
-    - uses: vapier/coverity-scan-action@v1
-      with:
-        build_language: 'cxx'
-        project: "eclipse/mosquitto"
-        token: ${{ secrets.COVERITY_SCAN_TOKEN }}
-        email: ${{ secrets.COVERITY_SCAN_EMAIL }}
-        command: "make binary"
-