ci(renovate): Improve version detection regex

renovate.json

@@ -35,7 +35,7 @@
     {
       "fileMatch": ["images/mirror/Earthfile$"],
       "matchStrings": [
-        "DO \\+MIRROR --image=\"?'?(?<depName>[^:\\s]+?):(?<currentValue>[^\"]*?)@?(?<currentDigest>sha256:[a-f0-9]+)?\"?'?\\s"
+        "DO \\+MIRROR --image=\"?'?(?<depName>[^:\\s]+?):(?<currentValue>[a-z0-9-.]+?)?@?(?<currentDigest>sha256:[a-f0-9]+)?\"?'?\\s"
       ],
       "datasourceTemplate": "docker",
       "versioningTemplate": "docker"