Update dependabot.yml

Author: tkoyama010

.github/dependabot.yml

@@ -13,6 +13,8 @@ updates:
       pip:
         patterns:
           - "*"
+    commit-message:
+      prefix: "chore"
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
@@ -25,3 +27,5 @@ updates:
       actions:
         patterns:
           - "*"
+    commit-message:
+      prefix: "chore"