ci: switch star history chart to repo-growth action

.github/workflows/repo-growth.yml

@@ -0,0 +1,23 @@
+name: Update repository growth
+
+on:
+  schedule:
+    - cron: "17 4 * * *"
+  workflow_dispatch:
+
+permissions:
+  contents: write
+
+concurrency:
+  group: repo-growth
+  cancel-in-progress: false
+
+jobs:
+  update:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - uses: MacRimi/repo-growth@v1
+        with:
+          title: WeChat-AI growth
+          output: assets/repo-growth.svg

.github/workflows/star-history.yml

@@ -1,24 +0,0 @@
-name: Star History
-
-on:
-  schedule:
-    - cron: '0 */6 * * *'   # every 6 hours; see interval table below
-  watch:
-    types: [started]        # optional: also refresh right after a new star
-  workflow_dispatch:
-
-permissions:
-  contents: write
-
-concurrency:
-  group: star-history
-  cancel-in-progress: true  # collapse a burst of stars into one run
-
-jobs:
-  star-history:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: narayann7/star-history-action@v1
-        with:
-          repos: ${{ github.repository }}   # or a list: owner/repo,owner/repo2