imgtool: Install imgtool dependencies in fih-test

Install imgtool dependencies before tf-m build in fih-test to fix
failing ci job due to ImportError, originating from missing new types
added in cryptography library version 40.0.0.

Signed-off-by: Rustam Ismayilov <rustam.ismayilov@arm.com>
Change-Id: Id05f251024cf126d90d0fea22d21167329530f87

Author: rustammendel

ci/fih_test_docker/execute_test.sh

@@ -33,6 +33,9 @@ else
     CMAKE_FIH_LEVEL="-DMCUBOOT_FIH_PROFILE=\"$FIH_LEVEL\""
 fi
 
+# Install imgtool dependencies
+pip install -r $MCUBOOT_PATH/scripts/requirements.txt
+
 # build TF-M with MCUBoot
 mkdir -p $TFM_BUILD_DIR
 cd $TFM_DIR