fix: update cosign example in readme

Update cosign example in readme.

Signed-off-by: Charles-Edouard Brétéché <charles.edouard@nirmata.com>

README.md

@@ -64,7 +64,7 @@ jobs:
     name: Install Chainsaw
     steps:
       - name: Install Cosign
-        uses: sigstore/cosign-installer@v3.1.1
+        uses: sigstore/cosign-installer@v3.6.0
       - name: Install Chainsaw
         uses: kyverno/action-install-chainsaw@v0.1.0
         with:
@@ -112,4 +112,4 @@ The following optional inputs:
 
 ## Security
 
-Should you discover any security issues, please refer to Kyverno's [security process](https://github.com/kyverno/kyverno/blob/main/SECURITY.md)
+Should you discover any security issues, please refer to Kyverno's [security process](https://github.com/kyverno/kyverno/blob/main/SECURITY.md)