.github: switch to using renovate batched update prs

This is a suggestion to improve dependency upgrade PRs for bubbletea.

The provided renovate.json configuration batches updates into a single PR that
the bot keeps up to date with the latest versions of deps.

This helps to prevent pull request spam from dependabot + PR fatigue.

Signed-off-by: Christian Stewart <christian@aperture.us>

.github/renovate.json

@@ -0,0 +1,15 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    ":semanticPrefixFixDepsChoreOthers",
+    ":ignoreModulesAndTests",
+    "group:all",
+    "workarounds:all"
+  ],
+  "branchConcurrentLimit": 0,
+  "packageRules": [{
+    "matchManagers": ["gomod"],
+    "matchDepTypes": ["replace"],
+    "enabled": false
+  }]
+}