ci: change Docker workflow to run twice a month and on tag pushes

Change-Id: I2362073eba6df29db1ab1f054621805eb29429fd

.github/workflows/docker.yml

@@ -1,16 +1,11 @@
 name: Docker
 on:
   push:
-    branches:
-      - master
-    paths-ignore:
-      - '.editorconfig'
-      - '.jenkins'
-      - '.jenkins.d/**'
-      - 'launchd/**'
-      - '.mailmap'
-      - 'systemd/**'
-      - 'tests/**'
+    tags:
+      - 'NFD-*'
+  schedule:
+    # twice a month
+    - cron: '20 8 5,20 * *'
   workflow_dispatch:
 
 permissions:

Dockerfile

@@ -9,6 +9,7 @@ RUN apt-get install -Uy --no-install-recommends \
     # use 'apt-get distclean' when we upgrade to ubuntu:24.04
     && rm -rf /var/lib/apt/lists/*
 
+ARG JOBS
 RUN --mount=type=bind,rw,target=/src <<EOF
 set -eux
 cd /src