oniro-linux.conf: set preferred python version to 3.8.12

Set the preferred Python version to 3.8.12 with security
fixes.

Signed-off-by: Marta Rybczynska <marta.rybczynska@huawei.com>

meta-oniro-core/conf/distro/oniro-linux.conf

@@ -123,6 +123,8 @@ PREFERRED_PROVIDER_virtual/kernel_qemu-generic-arm64 = "linux-oniro"
 # qemu-generic-arm64 specific requirements
 PREFERRED_VERSION_optee-os_qemu-generic-arm64 = "3.14.0"
 
+PREFERRED_VERSION_python = "3.8.12"
+
 # Default to enabling serial debug console on RaspberryPi
 ENABLE_UART ?= "1"