updates to support python 3.6...<3.13

[smanders]

issue externpro/externpro#274

once an updated ubuntu buildpro image has been released (see issue externpro/externpro#272), the changes here will support building boost in a ubuntu container with gcc13

for now, a local build can be created by modifying .devcontainer (aka externpro) with the following

diff --git a/cmake/xptoplevel.cmake b/cmake/xptoplevel.cmake
index bf0b0a8..992cfc5 100644
--- a/cmake/xptoplevel.cmake
+++ b/cmake/xptoplevel.cmake
@@ -1,4 +1,4 @@
-set(buildpro_REV 25.06)
+set(buildpro_REV latest)
 include(xpfunmac)
 if(NOT DEFINED XP_SANITIZER)
   set(XP_SANITIZER "ASAN")

and executing the commands

./docker-compose.sh -u
cmake --preset=Linux
cmake --workflow --preset=LinuxRelease