feat(webnsupdate): add support for fritzbox style updates

Update now optionally accepts query params (e.g. `/update?ipv4=1.2.3.4`)
if present they will control how the update is made (only ipv4 and ipv6
are implemented right now).

Closes #80

.forgejo/workflows/check.yml

@@ -20,6 +20,8 @@ jobs:
           - module-ipv4-test
           - module-ipv6-test
           - module-nginx-test
+          - module-ipv4-only-test
+          - module-ipv6-only-test
     steps:
       - uses: https://git.salame.cl/actions/checkout@v4
       - name: Check