Group Compose compiler into Kotlin update PRs (#176)

renovate.json

@@ -1,6 +0,0 @@
-{
-	"$schema": "https://docs.renovatebot.com/renovate-schema.json",
-	"extends": [
-		"config:base"
-	]
-}

renovate.json5

@@ -0,0 +1,16 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    "config:base"
+  ],
+  "packageRules": [
+    {
+      // Compose compiler is tightly coupled to Kotlin version
+      "groupName": "Kotlin and Compose",
+      "matchPackagePrefixes": [
+        "org.jetbrains.compose.compiler",
+        "org.jetbrains.kotlin:kotlin",
+      ],
+    },
+  ],
+}