Update build-nightly.sh

Force some docker operations

tools/nightly22/build-nightly.sh

@@ -19,9 +19,9 @@ cd ${workdir}
 # Create on-demand build environment
 cp code/radio/util/Dockerfile .
 docker build -t new-$docker --build-arg OPENTX_VERSION_SUFFIX=$suffix .
-docker rmi $docker || true
+docker rmi -f $docker || true
 docker tag new-$docker $docker
-docker rmi new-$docker
+docker rmi -f new-$docker
 
 # Call sdcard generation
 code/tools/nightly22/build-sdcard.sh