Test snippets are not tested in CI

[rbalint]

make -C test/ snippets fails for me locally:

$ make -C test/ snippets 
make: Entering directory '/home/rbalint/projects/deb/libfaketime/test'
./test_variable_data.sh clock_gettime_heap clock_gettime getentropy getpid getrandom time
[getentropy] Set FAKERANDOM_SEED="0x0123456789ABCDEF", but got two different outputs:
 - [run_getentropy] getentropy() yielded 0x47051e90
 - [run_getentropy] getentropy() yielded 0x1fb8736b
[getpid] Set FAKETIME_FAKEPID="1", but got two different outputs:
 - [run_getpid] getpid() yielded 559510
 - [run_getpid] getpid() yielded 559511
[getrandom] Set FAKERANDOM_SEED="0xDEADBEEFDEADBEEF", but got two different outputs:
 - [run_getrandom] getrandom() yielded 0xe1c03fc7
 - [run_getrandom] getrandom() yielded 0x0ff37b00
Sleeping 2 seconds...done
[getentropy] Vary across delay of 2 seconds (FAKERANDOM_SEED="0x0123456789ABCDEF"):
 - before: [run_getentropy] getentropy() yielded 0x47051e90
 -  after: [run_getentropy] getentropy() yielded 0x00482623
[getpid] Vary across delay of 2 seconds (FAKETIME_FAKEPID="1"):
 - before: [run_getpid] getpid() yielded 559510
 -  after: [run_getpid] getpid() yielded 559526
[getrandom] Vary across delay of 2 seconds (FAKERANDOM_SEED="0xDEADBEEFDEADBEEF"):
 - before: [run_getrandom] getrandom() yielded 0xe1c03fc7
 -  after: [run_getrandom] getrandom() yielded 0xfb4e877e
Got 6 errors, failing
make: *** [Makefile:59: test_variable_data] Error 1
make: Leaving directory '/home/rbalint/projects/deb/libfaketime/test'