Update update_lets_encrypt_certificate.yml

Author: JackPGreen

.github/workflows/update_lets_encrypt_certificate.yml

@@ -24,7 +24,6 @@ jobs:
         with:
           repository: hazelcast/hazelcast-python-client
           path: client
-          ref: master
       - name: Copy updated certificate
         run: |
           cp $GITHUB_WORKSPACE/certs/com/hazelcast/nio/ssl/letsencrypt.jks $GITHUB_WORKSPACE/client/tests/integration/backward_compatible/ssl_tests/keystore.jks