Updated url path of u-boot for secure-boot imx6 test case

Signed-off-by: Abhinish Kumar external.abhinish.kumar@in.bosch.com

test-cases/secure-boot-imx6.yaml

@@ -15,7 +15,7 @@ metadata:
   pre-conditions:
     - "Requires the DUT to be flashed with a signed U-Boot built with HAB and FIT image support
       as provided since version 2019.01+dfsg-7co6. U-Boot could be installed with
-      [public U-Boot installer v2021.0](https://images.apertis.org/release/v2021/v2021.0/installer/mx6qsabrelite-uboot/)
+      [public U-Boot installer v2023.0](https://images.apertis.org/release/v2023/v2023.0/installer/mx6qsabrelite-uboot/)
       or any newer version."
     - "Requires a DUT with fused SRK hash (it's a irreversible operation! Please refer to the documentation).
       Or use additional step for 'emulation' if fusing is not possible. Skip it if the board has fused SRK."