Add keys for tls13 compat tests

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/tests/data_files/ecdsa_secp384r1_sha384.crt b/tests/data_files/ecdsa_secp384r1_sha384.crt
new file mode 100644
index 0000000..f118d93
--- /dev/null
+++ b/tests/data_files/ecdsa_secp384r1_sha384.crt
@@ -0,0 +1,11 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----