tensorflow version including security patch

https://github.com/advisories/GHSA-57wx-m983-2f88
diff --git a/CMSIS/NN/Tests/UnitTest/requirements.txt b/CMSIS/NN/Tests/UnitTest/requirements.txt
index 3f1dff4..aed2156 100644
--- a/CMSIS/NN/Tests/UnitTest/requirements.txt
+++ b/CMSIS/NN/Tests/UnitTest/requirements.txt
@@ -77,7 +77,7 @@
 tensorboard==2.6.0
 tensorboard-data-server==0.6.1
 tensorboard-plugin-wit==1.8.0
-tensorflow==2.6.0
+tensorflow==2.6.1
 tensorflow-estimator==2.6.0
 termcolor==1.1.0
 transitions==0.8.9