.github: drop sync job in favor of local cronjob

[skip ci]

Resolves: #572

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

.github/workflows/sync-fork.yml

@@ -1,28 +0,0 @@
-# To enable automatic sync of your Infix fork every day, or on dispatch,
-# set the repoistory or organisation variable (not secret):
-#
-#     SYNC_FORK = true
-#
-# You also need a GH_SYNC_REPO token allowed to update workflows.  For
-# more information on variables and secrets, see the GitHub docs.
-# See https://docs.github.com/en/actions/learn-github-actions/variables
-name: Synchronize your fork of Infix with upstream
-
-on:
-  schedule:
-    - cron: 42 2 * * *
-  workflow_dispatch:
-
-jobs:
-  sync_fork:
-    if: ${{github.repository_owner != 'kernelkit' && vars.SYNC_FORK == 'true' }}
-    runs-on: ubuntu-latest
-    steps:
-      - uses: TobKed/github-forks-sync-action@master
-        with:
-          github_token: ${{ secrets.GH_SYNC_REPO }}
-          upstream_repository: KernelKit/infix
-          upstream_branch: main
-          target_branch: main
-          force: false
-          tags: true