remove bashism for setting --enable-nightly
for the past few nights the wheels have not been built with the --enable-nightly flag, this was added using:
if [[ ${CI_PIPELINE_SOURCE} == schedule ]]; then EXTRA_CONFIG_FLAGS="--enable-nightly"; fi
and [[ ]] is a bash extension, as the default non-interactive shell in Debian is /bin/dash, is this the source of the problem. Modify the test to be POSIX complient.
refs #59 (closed)
[ci skip]