[CI:BUILD] FCOS image: enable nightly build

`wait-for-copr` is still very flaky and has failed more often than not.
Ref: https://github.com/fedora-copr/copr/issues/2819

This change to the fcos GHA will allow nightly builds pulling in
whatever packages exist on podman-next at that time without depending on
wait-for-copr.

The commit id will still be recorded in podman version as well as the
image tag, so auditing is not affected with this change.

[NO NEW TESTS NEEDED]

Signed-off-by: Lokesh Mandvekar <lsm5@fedoraproject.org>

.github/workflows/fcos-podman-next-build.yml

@@ -4,6 +4,9 @@ on:
   push:
     branches:
       - main
+  # Run everyday at midnight and pull the latest packages from the copr
+  schedule:
+    - cron: '0 0 * * *'
 
 env:
   IMAGE_NAME: fcos
@@ -24,6 +27,8 @@ jobs:
         sudo apt -y install qemu-user-static
 
     - name: Set up wait-for-copr
+      # Do not run on scheduled nightly builds
+      if: ${{ github.event_name }} != 'schedule'
       run: |
         pip3 install git+https://github.com/packit/wait-for-copr.git@main
 
@@ -35,6 +40,8 @@ jobs:
       id: short_sha
 
     - name: Wait for successful podman-next build with the latest commit
+      # Do not run on scheduled nightly builds
+      if: ${{ github.event_name }} != 'schedule'
       run: |
         # TODO: add this in the Containerfile itself or as a --build-arg
         wait-for-copr --owner ${{ env.COPR_OWNER }} --project ${{ env.COPR_PROJECT }} podman ${{ env.SHORT_SHA }}