Make all bash verify scripts fail on error

Bash scripts by default continue on executing even if any
command errors. That's not the behavior we want for our scripts,
so let's explicitly get them to fail if:

1. Any command exits with non 0 exit code
2. An undefined variable is referenced

tests/dockerfile/binder-dir/verify

@@ -1,3 +1,3 @@
 #!/bin/sh
-set -e
+set -euo pipefail
 /usr/local/bin/sayhi.sh

tests/dockerfile/simple/verify

@@ -1,3 +1,3 @@
 #!/bin/sh
-set -e
+set -euo pipefail
 /usr/local/bin/sayhi.sh

tests/venv/apt-packages/verify

@@ -1,2 +1,3 @@
 #!/bin/bash
+set -euo pipefail
 which gfortran

tests/venv/binder-dir/verify

@@ -1,4 +1,5 @@
 #!/bin/bash
+set -euo pipefail
 which gfortran
 test -z $(pip list | grep scipy)
 jupyter nbextension list

tests/venv/postBuild/verify

@@ -1,3 +1,3 @@
 #!/bin/bash
-set -e
+set -euo pipefail
 jupyter nbextension list | grep 'jupyter-leaflet' | grep enabled