Update Renovate configuration (#659)

Co-authored-by: otelbot <197425009+otelbot@users.noreply.github.com>
Co-authored-by: Trask Stalnaker <trask.stalnaker@gmail.com>

Author: 3 people

.github/renovate.json5

@@ -1,7 +1,8 @@
 {
   "$schema": "https://docs.renovatebot.com/renovate-schema.json",
   "extends": [
-    "config:recommended",
+    "config:best-practices",
+    "helpers:pinGitHubActionDigestsToSemver",
     "customManagers:dockerfileVersions" // used by logging-k8s-stdout-otlp-json/Dockerfile
   ],
   "packageRules": [