removing adder_trees from task_list (issue #1770)

Author: ArashAhmadian

vtr_flow/tasks/regression_tests/vtr_reg_nightly_test1/task_list.txt

@@ -1,7 +1,9 @@
+#Refer to Issue #1770 for details. 
+#regression_tests/vtr_reg_nightly_test1/arithmetic_tasks/adder_trees
+
 regression_tests/vtr_reg_nightly_test1/vpr_reg_mcnc
 regression_tests/vtr_reg_nightly_test1/vtr_reg_fpu_soft_logic_arch
 regression_tests/vtr_reg_nightly_test1/vtr_reg_fpu_hard_block_arch
-regression_tests/vtr_reg_nightly_test1/arithmetic_tasks/adder_trees
 regression_tests/vtr_reg_nightly_test1/arithmetic_tasks/figure_8
 regression_tests/vtr_reg_nightly_test1/arithmetic_tasks/FIR_filters
 regression_tests/vtr_reg_nightly_test1/arithmetic_tasks/FIR_filters_frac