fix: Ensure lowercase GitHub image namespace

entrypoint.sh

@@ -25,10 +25,11 @@ sanitize "${IMAGE}" "image"
 sanitize "${TAG}" "tag"
 
 if [ "$REGISTRY" == "docker.pkg.github.com" ]; then
-    export IMAGE="$GITHUB_REPOSITORY/$IMAGE"
+    IMAGE_NAMESPACE="$(echo $GITHUB_REPOSITORY | tr '[:upper:]' '[:lower:]')"
+    export IMAGE="$IMAGE_NAMESPACE/$IMAGE"
 
     if [ ! -z $INPUT_CACHE_REGISTRY ]; then
-        export INPUT_CACHE_REGISTRY="$REGISTRY/$GITHUB_REPOSITORY/$INPUT_CACHE_REGISTRY"
+        export INPUT_CACHE_REGISTRY="$REGISTRY/$IMAGE_NAMESPACE/$INPUT_CACHE_REGISTRY"
     fi
 fi
 

renovate.json

@@ -0,0 +1,5 @@
+{
+  "extends": [
+    "config:base"
+  ]
+}