Bump MINOR to 21

Author: kmazurki

IGC/CMakeLists.txt

@@ -35,7 +35,7 @@ if(NOT DEFINED IGC_API_MAJOR_VERSION)
   set(IGC_API_MAJOR_VERSION 2)
 endif()
 if(NOT DEFINED IGC_API_MINOR_VERSION)
-  set(IGC_API_MINOR_VERSION 20)
+  set(IGC_API_MINOR_VERSION 21)
 endif()
 if(NOT DEFINED IGC_API_PATCH_VERSION)
   set(IGC_API_PATCH_VERSION 0)