Update source repo in BCR metadata.json (#2672)

Update after https://github.com/bazel-contrib/rules_python/issues/2638

.bcr/metadata.template.json

diff --git a/.bcr/metadata.template.json b/.bcr/metadata.template.json
index b164e70..579d688 100644
--- a/.bcr/metadata.template.json
+++ b/.bcr/metadata.template.json
@@ -13,7 +13,8 @@
     }
   ],
   "repository": [
-    "github:bazelbuild/rules_python"
+    "github:bazelbuild/rules_python",
+    "github:bazel-contrib/rules_python"
   ],
   "versions": [],
   "yanked_versions": {}