Fix version detection for liquidsoap CI build Docker image.

renovate.json

@@ -4,8 +4,19 @@
   ],
   "packageRules": [
     {
-      "matchUpdateTypes": ["minor", "patch", "pin", "digest"],
+      "matchUpdateTypes": [
+        "minor",
+        "patch",
+        "pin",
+        "digest"
+      ],
       "automerge": true
+    },
+    {
+      "matchPackageNames": [
+        "savonet/liquidsoap-ci-build"
+      ],
+      "versioning": "regex:^v?(?<major>\\d+)\\.(?<minor>\\d+)\\.(?<patch>\\d+)?(_(?<compatibility>.+))?$"
     }
   ],
   "regexManagers": [
@@ -22,4 +33,4 @@
       "packageNameTemplate": "homebrew/{{{ lowercase depNameUppercase }}}"
     }
   ]
-}
+}