CI: Ignore unbound variables in scripts/docker-*.sh

scripts/docker-build.sh

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 
-set -eu
+set -e
 
 # see https://docs.docker.com/develop/develop-images/build_enhancements/#to-enable-buildkit-builds
 export DOCKER_BUILDKIT=1

scripts/docker-buildx.sh

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 
-set -eu
+set -e
 
 # see https://docs.docker.com/develop/develop-images/build_enhancements/#to-enable-buildkit-builds
 export DOCKER_BUILDKIT=1

scripts/docker-push.sh

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 
-set -eu
+set -e
 
 if [[ -z $DOCKER_PASSWORD ]] || [[ -z $DOCKER_USERNAME ]]; then
     docker login