Failed tests still produce exit code of 0 (zero)

[Mierdin]

Running a test that results in success, as expected, produces an exit code of 0:

~$ jsnapy --snapcheck -f jsnapyconfig.yaml -v
Tests Included : test_applications
Taking snapshot of RPC: get-config
***************************** Device: 127.0.0.1 *****************************
Tests Included: test_applications
*************************RPC is get-config*************************
----------------------Performing is-equal Test Operation----------------------
Test Succeeded!!, destination-port is <30589>
PASS | All "destination-port" is equal to "30589" [ 1 matched ]
------------------------------- Final Result!! -------------------------------
test_applications : Passed
Total No of tests passed: 1
Total No of tests failed: 0
Overall Tests passed!!!

~$ echo $?
0

However, a failing test also produces a 0:

~$ jsnapy --snapcheck -f jsnapyconfig.yaml -v
Tests Included : test_applications
Taking snapshot of RPC: get-config
***************************** Device: 127.0.0.1 *****************************
Tests Included: test_applications
*************************RPC is get-config*************************
----------------------Performing is-equal Test Operation----------------------
Test Failed!!!, destination-port is <30589>
FAIL | All "destination-port" is not equal to "12345" [ 0 matched / 1 failed ]
------------------------------- Final Result!! -------------------------------
test_applications : Failed
Total No of tests passed: 0
Total No of tests failed: 1
Overall Tests failed!!!

~$ echo $?
0

This isn't ideal for running jsnapy in a network automation pipeline, where network changes may or may not continue based on whether or not these tests passed. Should return a nonzero exit code to indicate one or more tests didn't pass.