Fix checker locale for task score formatting

This fix adds a line to both task-1 and bonus checkers, setting LC_ALL to the
default "C" locale.

This is necessary as other locales like ro_RO.UTF-8 cause numbers to be
displayed with a comma instead of a dot for the floating point separator. In
that case, the local Python checker script throws errors when looking for a
dot-formatted number with basic regex in the task-specific checker output.

Signed-off-by: Cosmin Popa <cosmin7popa@gmail.com>