terraform-providers.grafana: Fix download URL.

Apologies for the pushes straight to release without PR, I will follow
the new workflow moving forward. Unfortunately my last push broke the
package in a way that was invisible locally due to the source already
being downloaded... A perfect example of why we should let ofborg
build!

pkgs/applications/networking/cluster/terraform-providers/providers.json

@@ -377,7 +377,8 @@
     "version": "3.47.0"
   },
   "grafana": {
-    "owner": "terraform-providers",
+    "owner": "grafana",
+    "provider-source-address": "registry.terraform.io/grafana/grafana",
     "repo": "terraform-provider-grafana",
     "rev": "v1.12.0",
     "sha256": "0jqm8ql8kams2rh90fwdmv9nnf4npzpxaagm9725nsf0iqn3qlhn",