[CI] enable dependabot for GHA workflows (#950)

* chore: add .editorconfig

* feat: enable dependabot for GHA workflows

Author: XuehaiPan

.editorconfig

@@ -0,0 +1,41 @@
+# https://editorconfig.org/
+
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_style = space
+indent_size = 4
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.{py,pyi}]
+indent_size = 4
+
+[*.{cpp,hpp,cxx,cc,c,h,cu,cuh}]
+indent_size = 4
+
+[*.{yaml,yml}]
+indent_size = 2
+
+[.clang-{format,tidy}]
+indent_size = 2
+
+[Makefile]
+indent_style = tab
+
+[*.sh]
+indent_size = 4
+
+[*.bat]
+indent_size = 4
+end_of_line = crlf
+
+[*.md]
+indent_size = 2
+x-soft-wrap-text = true
+
+[*.rst]
+indent_size = 4
+x-soft-wrap-text = true

.github/dependabot.yml

@@ -0,0 +1,11 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+      day: "monday"
+      time: "12:00"
+      timezone: "Asia/Shanghai"
+    commit-message:
+      prefix: "[CI]"