ha-mcp: restrict update script to release versions

The upstream repo tags both releases (v6.6.1) and dev builds
(v6.6.1.dev211). Without a version regex, the update bot picks up dev
tags and opens spurious PRs (e.g. #490377).

Add a --version-regex that matches only three-segment release versions.

pkgs/by-name/ha/ha-mcp/package.nix

@@ -2,6 +2,7 @@
   lib,
   python3Packages,
   fetchFromGitHub,
+  nix-update-script,
 }:
 
 python3Packages.buildPythonApplication (finalAttrs: {
@@ -37,6 +38,10 @@ python3Packages.buildPythonApplication (finalAttrs: {
   # Tests require a running Home Assistant instance
   doCheck = false;
 
+  passthru.updateScript = nix-update-script {
+    extraArgs = [ "--version-regex=^v([0-9]+\\.[0-9]+\\.[0-9]+)$" ];
+  };
+
   pythonImportsCheck = [ "ha_mcp" ];
 
   meta = {