Update schema URL

custom-checks.json

 {
-    "$schema": "https://git.opendatafrance.net/validata/validata-py/raw/master/custom_checks_schema.json",
+    "$schema": "https://git.opendatafrance.net/validata/custom-checks-schema/raw/v0.1/custom_checks_schema.json",
     "title": "Validations personnalisées en complément du schéma SCDL Base d'adresses locales",
     "author": "Pierre Dittgen, Jailbreak",
     "version": "0.1",