Add missing client certificate check in handshake defragmentation tests

Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 1b3708f..b62a7c1 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -14460,6 +14460,7 @@
 # Handshake defragmentation testing
 
 requires_openssl_tls1_3
+requires_certificate_authentication
 run_test    "Client Handshake defragmentation (512)" \
             "$O_NEXT_SRV -max_send_frag 512 " \
             "$P_CLI debug_level=4 " \
@@ -14468,6 +14469,7 @@
             -c "handshake fragment: "
 
 requires_openssl_tls1_3
+requires_certificate_authentication
 run_test    "Client Handshake defragmentation (513)" \
             "$O_NEXT_SRV -max_send_frag 513 " \
             "$P_CLI debug_level=4 " \