Add python3 install

ignition/base-install-python3.ign

@@ -0,0 +1,14 @@
+{
+  "ignition": {
+    "version": "3.5.0"
+  },
+  "systemd": {
+    "units": [
+      {
+        "contents": "[Unit]\nDescription=Install Python3\nWants=network-online.target\nAfter=ignition-start-config.service\nBefore=zincati.service\nConditionPathExists=!/var/lib/%N.stamp\n\n[Service]\nType=oneshot\nRemainAfterExit=yes\nExecStart=/usr/bin/rpm-ostree install python3\nExecStart=/usr/bin/touch /var/lib/%N.stamp\nExecStart=/usr/bin/systemctl --no-block reboot\n\n[Install]\nWantedBy=multi-user.target",
+        "enabled": true,
+        "name": "rpm-ostree-install-python3.service"
+      }
+    ]
+  }
+}