Fixed the PR number in Artifacthub note

Author: pierluigilenoci

helm/oauth2-proxy/Chart.yaml

@@ -35,4 +35,4 @@ annotations:
       description: Updated OAuth2-Proxy image to v7.11.0
       links:
         - name: Github PR
-          url: https://github.com/oauth2-proxy/manifests/pull/328
+          url: https://github.com/oauth2-proxy/manifests/pull/329