Configure Renovate (#6)

* Create reusable PHPStan workflow

* Bump actions/checkout from 3 to 4 (#4)

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Delete php-build.yml

Co-Authored-By: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* Add renovate.json

---------

Co-authored-by: Adam Daley <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

.github/renovate.json

@@ -0,0 +1,16 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    "config:recommended",
+    "schedule:weekly",
+    ":automergeDigest",
+    ":automergeMinor",
+    ":automergeRequireAllStatusChecks",
+    ":combinePatchMinorReleases",
+    ":prHourlyLimit2",
+    ":rebaseStalePrs"
+  ],
+  "automergeSchedule": ["at any time"],
+  "automergeStrategy": "squash",
+  "automergeType": "branch"
+}