Fix badge URL and action reference to flatt-security org

Author: ren-

README.md

@@ -5,7 +5,7 @@
 </p>
 
 <p align="center">
-  <a href="https://github.com/shisho-security/setup-takumi-guard-npm/actions"><img src="https://github.com/shisho-security/setup-takumi-guard-npm/actions/workflows/test.yml/badge.svg" alt="CI" /></a>
+  <a href="https://github.com/flatt-security/setup-takumi-guard-npm/actions"><img src="https://github.com/flatt-security/setup-takumi-guard-npm/actions/workflows/test.yml/badge.svg" alt="CI" /></a>
 </p>
 
 ## Usage
@@ -19,7 +19,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - uses: shisho-security/setup-takumi-guard-npm@v1
+      - uses: flatt-security/setup-takumi-guard-npm@v1
         with:
           bot-id: "BT01EXAMPLE..."  # from Shisho Cloud console