ci: bump main Python version to 3-13

Author: RobPasMue

.github/workflows/ci_cd.yml

@@ -9,7 +9,7 @@ on:
       - main
 
 env:
-  MAIN_PYTHON_VERSION: '3.12'
+  MAIN_PYTHON_VERSION: '3.13'
   PACKAGE_NAME: 'ansys-geometry-core'
   DOCUMENTATION_CNAME: 'geometry.docs.pyansys.com'
   ANSRV_GEO_IMAGE: 'ghcr.io/ansys/geometry'

.github/workflows/nightly_docker_test.yml

@@ -21,7 +21,7 @@ on:
       - v*
 
 env:
-  MAIN_PYTHON_VERSION: '3.12'
+  MAIN_PYTHON_VERSION: '3.13'
   ANSRV_GEO_IMAGE_WINDOWS_CORE_TAG: ghcr.io/ansys/geometry:core-windows-latest-unstable
   ANSRV_GEO_IMAGE_LINUX_CORE_TAG: ghcr.io/ansys/geometry:core-linux-latest-unstable
   ANSRV_GEO_PORT: 710