qemu_v8: Pin optee_rust to the latest version

Pin optee_rust to "Add expect script for OP-TEE CI".

Signed-off-by: Yuan Zhuang <zhuangyuan04@baidu.com>
Acked-by: Jerome Forissier <jerome@forissier.org>
diff --git a/qemu_v8.xml b/qemu_v8.xml
index d924691..911bea0 100644
--- a/qemu_v8.xml
+++ b/qemu_v8.xml
@@ -23,7 +23,7 @@
         <project path="buildroot"            name="buildroot/buildroot.git"               revision="refs/tags/2021.08" clone-depth="1" />
         <project path="edk2"                 name="tianocore/edk2.git"                    revision="refs/tags/edk2-stable202105" sync-s="true" />
         <project path="mbedtls"              name="ARMmbed/mbedtls.git"                   revision="refs/tags/mbedtls-2.26.0" clone-depth="1" />
-        <project path="optee_rust"           name="apache/incubator-teaclave-trustzone-sdk.git"            revision="dfd51b7286407070e40b23defe6cef33f4f120c7" />
+        <project path="optee_rust"           name="apache/incubator-teaclave-trustzone-sdk.git"            revision="8520a2018705edcebfb7e729bd2ced12414fc052" />
         <project path="qemu"                 name="qemu/qemu.git"                         revision="refs/tags/v6.0.0" clone-depth="1" />
         <project path="trusted-firmware-a"   name="TF-A/trusted-firmware-a.git"           revision="refs/tags/v2.5" clone-depth="1" remote="tfo" />
         <project path="u-boot"               name="u-boot.git"                            revision="refs/tags/v2021.04" remote="u-boot" clone-depth="1" />