DEV: adjust renovate rangeStrategy and fix syntax (#211)

* DEV: fix renovate.json syntax

* DEV: renovate: use `bump` for `rangeStrategy`

Author: lucascolley

renovate.json

@@ -2,9 +2,10 @@
   "$schema": "https://docs.renovatebot.com/renovate-schema.json",
   "extends": ["config:recommended"],
   "dependencyDashboardTitle": "META: Dependency Dashboard",
+  "rangeStrategy": "bump",
   "packageRules": [
     {
-      "matchManager": ["pixi"],
+      "matchManagers": ["pixi"],
       "matchCurrentValue": "/^~?=/",
       "enabled": false
     }