add valgrind to CI

[jacobwilliams]

Maybe run valgrind in the CI to check for memory leaks.

[jacobwilliams]

The following tests are showing memory leaks:

• jf_test_12
• jf_test_15
• jf_test_25
• jf_test_27
• jf_test_37
• jf_test_39
• jf_test_41
• jf_test_46
• jf_test_50 -- fixed in c41a0c0

[jacobwilliams]

For case 12, this is the memory leak:

my_file = json_file(root,verbose=.true.,real_format='G')

Not sure if it's the assignment or the json_file interface or some combination of both that is causing it.

Is it a real bug, or just a gfortran bug with not calling the finalizers correctly?

Assignments like my_file2 = my_file don't seem to cause memory leaks.

[jacobwilliams]

All of them (except 50) have this same issue.