docker: add libsgx-headers
diff --git a/dockerfile/04_psw.sh b/dockerfile/04_psw.sh
index f565cfe..2b89a32 100644
--- a/dockerfile/04_psw.sh
+++ b/dockerfile/04_psw.sh
@@ -2,6 +2,7 @@
     add-apt-repository "deb https://download.01.org/intel-sgx/sgx_repo/ubuntu $CODENAME main" && \
     apt-get update && \
     apt-get install -y \
+        libsgx-headers=$VERSION \
         libsgx-ae-epid=$VERSION \
         libsgx-ae-le=$VERSION \
         libsgx-ae-pce=$VERSION \