chore: add flux renovate group

Signed-off-by: Devin Buhl <devin@buhl.casa>

.github/renovate.json5

@@ -10,6 +10,7 @@
     ":automergeBranch",
     "github>onedr0p/flux-cluster-template//.github/renovate/autoMerge.json5",
     "github>onedr0p/flux-cluster-template//.github/renovate/commitMessage.json5",
+    "github>onedr0p/flux-cluster-template//.github/renovate/groups.json5",
     "github>onedr0p/flux-cluster-template//.github/renovate/labels.json5",
     "github>onedr0p/flux-cluster-template//.github/renovate/semanticCommits.json5",
     "helpers:pinGitHubActionDigests"

.github/renovate/groups.json5

@@ -0,0 +1,15 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "packageRules": [
+    {
+      "description": "Flux images and tags",
+      "groupName": "Flux",
+      "matchPackagePatterns": ["flux"],
+      "matchDatasources": ["docker", "github-tags"],
+      "group": {
+        "commitMessageTopic": "{{{groupName}}} group"
+      },
+      "separateMinorPatch": true
+    }
+  ]
+}