docs: Update setup-regal in docs (#1964)

* docs: Update setup-regal in docs

This pointed to a very old release of the setup action

Signed-off-by: Charlie Egan <charlie_egan@apple.com>

* Bump actions/checkout from v4 to v6

Update checkout action version in CI lint-rego example.

Signed-off-by: Charlie Egan <charlie_egan@apple.com>

---------

Signed-off-by: Charlie Egan <charlie_egan@apple.com>

Author: charlieegan3

docs/cicd.md

@@ -19,8 +19,8 @@ jobs:
   lint-rego:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
-    - uses: open-policy-agent/setup-regal@v1
+    - uses: actions/checkout@v6
+    - uses: open-policy-agent/setup-regal@v2
       with:
         # For production workflows, use a specific version, like v0.22.0
         version: latest