backed out update of pybind11

Author: dkeeney

external/pybind11.cmake

@@ -21,7 +21,8 @@
 if(EXISTS "${REPOSITORY_DIR}/build/ThirdParty/share/pybind11.tar.gz")
     set(URL "${REPOSITORY_DIR}/build/ThirdParty/share/pybind11.tar.gz")
 else()
-    set(URL "https://github.com/pybind/pybind11/archive/refs/tags/v2.9.2.tar.gz")
+    set(URL https://github.com/pybind/pybind11/archive/v2.6.2.tar.gz)
+#    set(URL "https://github.com/pybind/pybind11/archive/refs/tags/v2.9.2.tar.gz")
 endif()
 
 message(STATUS "obtaining PyBind11")