Merge branch 'pu/test-suite-shellcheck' of https://github.com/guillemj/liburing
* 'pu/test-suite-shellcheck' of https://github.com/guillemj/liburing:
test: Disable shellcheck checks
test: Declare and assign shell variable separately to not mask return value
test: Do not use $ in variables within $(())
test: Add missing quotes around variables
test: Pass an array to run_tests instead of an undefined variable
test: Use an array instead of interpolating into a string via $@
test: Use -z instead of ! -n
test: Use -n instead of ! -z
