Fix usage of mac address patterns in schema.py to allow using variables

Hello,
Everytime i try to add a variable to BSSID field on a WiFi interface configured as station,
It breaks the JSON configuration after/during saving.

ie,

        {
            "wireless": {
                "network": [
                    "lan"
                ],
                "mode": "station",
                "radio": "radio1",
                "ssid": "{{wireless_wlan0sta_ssid}}",
                "bssid": "00:11:22:33:44:55",
                "wds": true,
                "encryption": {
                    "protocol": "wpa2_personal",
                    "key": "{{wireless_wlan0sta_key}}",
                    "cipher": "ccmp",
                    "ieee80211w": "1"
                }
            },
            "type": "wireless",
            "name": "radio1sta",
            "network": "wlan1sta"
        },

becomes

        {
            "type": "ethernet",
            "name": "radio1sta",
            "network": "wlan1sta",
            "wireless": {
                "network": [
                    "lan"
                ],
                "mode": "station",
                "radio": "radio1",
                "ssid": "{{wireless_wlan1sta_ssid}}",
                "bssid": "{{wireless_wlan1sta_bsid}}",
                "wds": true,
                "encryption": {
                    "protocol": "wpa2_personal",
                    "key": "{{wireless_wlan1sta_key}}",
                    "cipher": "ccmp",
                    "ieee80211w": "1"
                }
            }
        }

I haven't looked at the code but i can try make a PR sometime later if i find the issue

Start in schema.py and reproduce the save operation using the station WiFi configuration shown in the issue, focusing on the MAC address pattern handling for the BSSID field. Done means a variable in BSSID remains intact after saving and the resulting configuration remains valid JSON.