Update stable version to 2.9.1

Release 2.9.1

Author: atalman

tools/scripts/generate_binary_build_matrix.py

@@ -78,7 +78,7 @@
 
 CURRENT_NIGHTLY_VERSION = "2.10.0"
 CURRENT_CANDIDATE_VERSION = "2.9.1"
-CURRENT_STABLE_VERSION = "2.9.0"
+CURRENT_STABLE_VERSION = "2.9.1"
 CURRENT_VERSION = CURRENT_STABLE_VERSION
 
 # By default use Nightly for CUDA arches