Revert "requirements: workaround networkx issue (#3507)"

This reverts commit ba7a0ec.

Author: mateusztabaka

tools/accuracy_checker/requirements.in

@@ -2,9 +2,6 @@
 tqdm>=4.54.1
 
 # image reading and preprocessing
-# networkx version upperbound in scikit-image is conflicted
-networkx~=2.5;python_version<"3.7"
-networkx<2.8.1;python_version>="3.7"
 # note: python 3.6 wheels is not available since 0.18
 scikit-image~=0.17.2;python_version<"3.7"
 scikit-image>=0.19.2;python_version>="3.7"