build: cache: Ensure shim-v2-root_hash.txt is in "${workdir}"

All the oras push logic happens from inside `${workdir}`, while the
root_hash.txt extraction and renaming was not taking this into
consideration.

This was not caught during the manually triggered runs as those do not
perform the oras push.

Signed-off-by: Fabiano Fidêncio <fabiano@fidencio.org>

tools/packaging/kata-deploy/local-build/kata-deploy-binaries.sh

@@ -1202,7 +1202,7 @@ handle_build() {
 					die "Building the shim-v2 with MEASURED_ROOTFS support requres a rootfs confidential image tarball built with MEASURED_ROOTFS support"
 				fi
 
-				mv root_hash.txt shim-v2-root_hash.txt
+				mv root_hash.txt ${workdir}/shim-v2-root_hash.txt
 			fi
 			;;
 	esac