Configure Renovate (#2)

* Add renovate.json

* github: Move renovate.json to .github dir and pin GitHub Actions digests to semver

---------

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Brad Keryan <[email protected]>

Author: renovate[bot]

.github/renovate.json

@@ -0,0 +1,8 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "branchPrefix": "users/renovate/",
+  "extends": [
+    "config:recommended",
+    "helpers:pinGitHubActionDigestsToSemver"
+  ]
+}